9070XT or 7900XT or 7900XTX

[Vayra86]

Sure , but its 1000$ or 2050 BGN for 4070 Ti SUper from zotac and 1833BGN from Inno3d I don't think any of these models are good ... There is one from MSI slim model , which is also 2000BGN (for refference , one minimum monthly salary here is 1080BGN)

Sure. The timing is just bad overall, is my message. If you need a card now, I guess go for it. If you can wait... wait. Blackwell and the 9070XT are just out there and the RDNA3 stock is drying up, so neither is in good supply.

That being said, the 9070XT looks better in every way compared to a 7900XT. But if its only raster you are after... and don't care about FSR4... its not a completely strange idea to pay about $100,- less for the 7900XT. That's a substantial difference, and I doubt it'll touch your gaming much. People are all worried about upcoming games with hard RT requirements... no need to be. It will be a handful of games at best, and the 7900XT will run them too, just not as well. The question is how highly you value those games. If you want to be on them the moment they release... 9070XT will probably earn itself back because you'll upgrade less early. I think that's really the most concrete, honest view on this. Money is money, and RT isn't a deal breaker for any gaming thus far - those are the facts.

As a user of the Asrock Phantom Gaming... its a very nice card overall, they've done a fine job. Built like a tank, does not sound like a jet plane, and cooling is adequate. I generally run it with a clock limit at 2500 mhz and during gaming its not really noticeable unless its working at full tilt (RT enabled titles), where 2500mhz is harder to achieve. And that's with the card pulling 250-300W in a pretty open air case. I like my silence. The card's pretty good at it.

This isn't a real question. You're on a 7700XT for a reason. If you need the extra power, you need additional power for it.
Not quite the tyranny of fuel equation but pretty similar. These high powered cards need LOTS of power.
If your machine runs on a 25A rail like my Antec 750W, you're going nowhere. Pick up a 1KW or better with high amps.
ALso the 9070XT while not a terrible investment itself can be a deep one depending on other things. Choose wisely.
I had the 7900XT in this system (x2) and did not have success with either one. I would not try again. Complete waste of time.

Wut... I'm running this card off an 850W PSU. No need to move to 1kW. A quality PSU though, certainly.

 

[Krit]

7900 XTX > 9070 XT > 9070 > 7900 XT > 7900 GRE, in that order of preference, assuming similar pricing

I would take RX 9070 XT over 7900 XTX if they are at the same price. There are no UV options for XTX which sucks also FSR4/RT.

 

[hermesa]

Sure. The timing is just bad overall, is my message. If you need a card now, I guess go for it. If you can wait... wait. Blackwell and the 9070XT are just out there and the RDNA3 stock is drying up, so neither is in good supply.

That being said, the 9070XT looks better in every way compared to a 7900XT. But if its only raster you are after... and don't care about FSR4... its not a completely strange idea to pay about $100,- less for the 7900XT. That's a substantial difference, and I doubt it'll touch your gaming much. People are all worried about upcoming games with hard RT requirements... no need to be. It will be a handful of games at best, and the 7900XT will run them too, just not as well. The question is how highly you value those games. If you want to be on them the moment they release... 9070XT will probably earn itself back because you'll upgrade less early. I think that's really the most concrete, honest view on this. Money is money, and RT isn't a deal breaker for any gaming thus far - those are the facts.

As a user of the Asrock Phantom Gaming... its a very nice card overall, they've done a fine job. Built like a tank, does not sound like a jet plane, and cooling is adequate. I generally run it with a clock limit at 2500 mhz and during gaming its not really noticeable unless its working at full tilt (RT enabled titles), where 2500mhz is harder to achieve. And that's with the card pulling 250-300W in a pretty open air case. I like my silence. The card's pretty good at it.


Wut... I'm running this card off an 850W PSU. No need to move to 1kW. A quality PSU though, certainly.

Thanks for the detailed answer to my concerns. Even more I want the 7900XT now.I love well built massive GPUs. I was looking into the 9070XT Hellhound white version and It didn't looked really premium at all.It is early model,maybe that's the reason. It have only 1 strip of RGB , the PCB(the plate of the gpu if that's called) is really short and small(remembers me of low-budget GPU's back in the years) and I don't know, It didn't looked that premium as the 7900XT build. The Phantom Gaming of 7900XT has really good design to be honest.

About the PSU - I was thinking a lot ,and in the end it turns out that this 1000W is somehow futureproofing and gives me big peace of mind for the ''spikes'' of that power hungry 7900XT that everyone talked about.Plus ,it have the premium sleeved white cables that I wanted to buy for 1 year now (no need to spend another 50$ for Cablemod) , it is suitable for my future upgrades on the AiO fans(I am thinking to replace that DeepCool default fans with x3 120mm Lian Li Uni infinity mirror + I have x2 Lian Li fans x140mm from the same kind and that HUB will be usefull someday. And it's 1000W gold for 350 BGN while the Corsair RM850x Shift is 850W gold for 340BGN , 5$ difference between them, so why not after all. I hope that it won't be sold to me some a ''lemon PSU unit'' of that brand and everything will be alright at the end.

I would take RX 9070 XT over 7900 XTX if they are at the same price. There are no UV options for XTX which sucks also FSR4/RT.

I don't know why , but somehow this situation reminds me when years ago I was on the crossroad between GTX 1650 Super and 1070Ti (I was even more unfamiliar with PC hardware,nowadays it's kinda the same but yeah ,whatever) I wanted to take the newer one ofcourse because it was newer and 1650>1070 , I was so excited to build any PC no matter what that at that moment I didn't paid any attention to the details (I ordered both of them and the courier guy was in the office and was waiting me to pick them up) and in the last moment of my decision I checked which one is better and the 1070Ti was superior to the 1650 Super even tho they had almost similar FPS in some games(or I am wrong , it was years before and I barely remember).Thank God I choose the 1070Ti and placed my bet on the raw performance one over the more power efficient GPU that back then was something ''new'' in the PC manufacturint. 1070Ti was great card for the time that I had it. I was never thinking back about what it would be with 1650Super. Right now I feel kinda the same , I prefer to bet on the better GPU on paper sheet,even more when I can't find my preferred games tested with the suggested one.I don't really buy a GPUs daily or monthly and I want my money to be wise spent for my needs, and that's why I want to bet on the ''secure'' one.

Surely the newer and more powerfull hardware nowadays will become smaller and more compact , but somehow I feel that the beefier and power hungry GPU hardwar(7900XT) is kinda more reliable.I know that this is not the case anymore in 2025 but..

 

[AVATARAT]

There are no UV options for XTX

This is not true, 7900 XTX can undervolt a lot.

 

[Krit]

This is not true, 7900 XTX can undervolt a lot.

At least RX 7900 XT was losing it's performance badly when undervolting. RX 7800 XT was way better.

It does not count if UV can not handle "stock performance" at lower watts.

 

[AVATARAT]

At least RX 7900 XT was losing it's performance badly when undervolting. RX 7800 XT was way better.

It does not count if UV can not handle "stock performance" at lower watts.

As someone who has had both 7900 XT/XTX, I can tell you that without undervolt you can't get high benchmarks/FPS in games.
Undervolt on this cards means more power limit and high frequency.

 

[Krit]

Undervolt on this cards means more power limit and high frequency.

At the higher power draw that is not undervolting it's just a overclocking (poor efficiency) that's way i don't like it.

For me UV is when lowering watts and at the same time not losing any performance RX 7900 XT just can't handle that....

 

[Dr. Dro]

I would take RX 9070 XT over 7900 XTX if they are at the same price. There are no UV options for XTX which sucks also FSR4/RT.

Depends on the situation I guess, but the 7900 XTX is still the most powerful between the two. 9070 XT is definitely more refined.

 

[Krit]

Depends on the situation I guess, but the 7900 XTX is still the most powerful between the two. 9070 XT is definitely more refined.

If we look at average raster and average RT i can not see a RX 7900 XTX as a faster gpu overall.

At raster they are close but when using RT XTX is clearly slower. For the same price it's a bad buy.

 

[Dr. Dro]

If we look at average raster and average RT i can not see a RX 7900 XTX as a faster gpu overall.

At raster they are close but when using RT XTX is clearly slower. For the same price it's a bad buy.

It's faster, even if by a hair. Does that make it worth it? Perhaps not, perhaps it does. Depends on the use case. The 9070 XT simply boosts the RT performance which has been completely abysmal on AMD up until this point. But since AMD fans spent the best part of the past 7 years saying RT is a worthless gimmick... As I've always said, something is bad until the Radeons can do it, then it's the best thing since sliced bread.

 

[Krit]

ut since AMD fans spent the best part of the past 7 years saying RT is a worthless gimmick...

It really is when it's overpriced crap like RTX 20/40 Series was. It's all about prices/value not brands.

Give me a better p/p nvidia gpu and i will buy it over AMD. It will not happen because AMD has edge in that area.

 

[RadeonRoller]

I have an XFX 7900XT Merc 310 Black Edition i bought last black friday for $589 after discounts and promos from newegg. In terms of PSU, I am using a be quiet! Straight Power 11 650W, BN618 80 Plus Gold unit, and it runs flawlessly, even with an OC. I would get a 9070xt instead of a 7900XT nowadays, but a 7900xt over the regular 9070 as its faster in raster. I paired it with 5700x3d and 48GB DDR4 @ 3600. All in all, a solid system that will last me for next 5 years, considering I used a RX 5700XT for the last 5 years.
Check out my OC timespy score. not too bad.

 

[RadeonRoller]

It really is when it's overpriced crap like RTX 20/40 Series was. It's all about prices/value not brands.

Give me a better p/p nvidia gpu and i will buy it over AMD. It will not happen because AMD has edge in that area.

The saying "there are no bad GPUs, only bad prices" applies now more than ever. A 7900XT for $550 is a good buy. If its anything more than that, its not worth it. Likewise, a 9070XT for more than ~$750 loses its appeal and is a bad value.

Also, I dont think I have ever seen FOMO when it comes to GPU purchases as bad as nowadays. I am talking about people with excellent GPUs like 4070 / Super and 7700XT and 7800XT upgrading. Never seen it this bad since I started PC gaming in 2010 (with the Phenom II X6 ). Maybe its just me who likes to wait 5-6 years between GPU upgrade cycles, and 7-8 years for CPU upgrades.

 

[Macro Device]

Maybe its just me who likes to wait 5-6 years between GPU upgrade cycles, and 7-8 years for CPU upgrades.

You're not alone here. If it wasn't for me giving up on my current PC I wouldn't bother buying anything for another couple years at least. But my bro's PC is way too ancient for the job I want him to do for me so I'm giving my PC to him and buying a brand new one for myself. That wasn't planned and I don't have the money yet... Eh. Hope the new one won't run into a similar emergency.

This FOMO is completely insane. Yesteryears, it had at least some reasoning behind it because mid range GPUs destroyed previous flagships but today if you bought a flagship it will stay decent for a decade. Is there anything unplayable on a 3080 Ti? Maybe some games won't be fine at 4K... Then imagine 2008 when you COULDN'T EVEN LAUNCH most games on your GPU from 2003, let alone monitor the FPS count.

 

[rusty caterpillar]

Sure. The timing is just bad overall, is my message. If you need a card now, I guess go for it. If you can wait... wait. Blackwell and the 9070XT are just out there and the RDNA3 stock is drying up, so neither is in good supply.

That being said, the 9070XT looks better in every way compared to a 7900XT. But if its only raster you are after... and don't care about FSR4... its not a completely strange idea to pay about $100,- less for the 7900XT. That's a substantial difference, and I doubt it'll touch your gaming much. People are all worried about upcoming games with hard RT requirements... no need to be. It will be a handful of games at best, and the 7900XT will run them too, just not as well. The question is how highly you value those games. If you want to be on them the moment they release... 9070XT will probably earn itself back because you'll upgrade less early. I think that's really the most concrete, honest view on this. Money is money, and RT isn't a deal breaker for any gaming thus far - those are the facts.

As a user of the Asrock Phantom Gaming... its a very nice card overall, they've done a fine job. Built like a tank, does not sound like a jet plane, and cooling is adequate. I generally run it with a clock limit at 2500 mhz and during gaming its not really noticeable unless its working at full tilt (RT enabled titles), where 2500mhz is harder to achieve. And that's with the card pulling 250-300W in a pretty open air case. I like my silence. The card's pretty good at it.


Wut... I'm running this card off an 850W PSU. No need to move to 1kW. A quality PSU though, certainly.

For PSU any decent 850 W ATX 3.0 will do just fine. ATX 3.0 should deal with any GPU spikes really. I believe 9070XT doesn't exceed 400W in spikes anyway.
Peak power excursion (ATX 2.x)=100%
Peak power excursion (ATX 3.0)=200%

As future proof PSU, well, in EU electricity will not become cheaper so any system which can not be handled by a 850W PSU is counterproductive in costs IMO.

As for the card, 9070XT clearly, lower power means less heat inside the case and in your room also less noise.

 

[alwayssts]

My 'short' suggestion is simply this:

1. Buy 9070 xt. Get your favorite assortment of stress tests ready. Or, you know, just play some games. BOLO any perf degradation (not just crashes) during the following.
2. Test memory limit (as this is the main constraint of almost every AMD GPU, this one included). I would start at 2700mhz; stay there if this 'not your thing', but more may help (~1-3% depending on model).
3. Lower voltage (uv/oc), testing thoroughly along the way. Perhaps start at ~ -40. This should raise the clock speed.
4. Lower power limit until performance is no longer acceptable to you, or it hits your personal goals for power consumption.

Voila', you've got about the best bang-for-buck you're going to get, along w/ decent power efficiency, which *should* (realistically) be enough for most peoples' scenarios.

If you can afford it, this is my suggestion to pretty much everyone right now. 4k may be fine for some games, 1440p for others, 1080p60 (1440p48) mins for Wukong. Very nice place to be for the price IMHO.
Should last a very long time, and scale generations well (ie: when 1440p native is no longer acceptable for you, 1440p up-scaling should last a good long while).

I think as more people buy these and do this very thing (getting 100fps in Time Spy; something even the weakest model in W1zard's testing can do, even if not 'optimal' compute/bw) people will understand.
This card is exactly what the market and people needed (granted I'd always be happy if prices stabilized and it were generally cheaper). Tweaked power consumption (especially for the perf tier) is also very good.

The weird thing about 9070 xt is the stock bw that gives it a very odd look of needing ~3-8% more perf (or better efficiency), but this is remedied if you're willing to take (varying amount of) time doing the above.
And really is quite an awesome card right now (for the price) if you're willing to do that IMHO.

I think there will be a lot of people pissed off to varying degrees when the next-gen (3nm?) low-end (think '600' level) performs similar (as that's where the market needs to be fairly-soon).

But you, you smart shopper, will be sitting just fine...arguably more ahead of the curve than *most* people, especially those with a similar budget right now. Not unlike a 4090 owner a tier above (at 4k).
Many that spent more aren't really going to 'get' more, realistically-speaking, and you can laugh about that too.

If I were the strange outlier of something like a 1440p 7900xtx owner, I'd be a little pissed off, but that's another story. That's also still not a 'bad' card for some people, just better longevity/utility if it had FSR4.
Ofc, 4090 owners have also been sleeping for over two years, but that's a different budget/perf requirement.

The only other option IMHO is buying/holding something to weather the storm until you can afford (when prices drop and/or a new gen with similar perf releases at lower prices) at least something similar.
Ofc, when prices stabalize and their relative (used) prices are worth it, which right now they generally are not imho. Hence 9070 xt becomes the go-to (if/when you can find one within your budget).

 

[AleXXX666]

Whichever is cheaper, take it... I'll prefer 7900XT if I were you...

 

[Durvelle27]

I’d go 9070XT if you can get one for MSRP

 

[alwayssts]

Whichever is cheaper, take it... I'll prefer 7900XT if I were you...

It's not a bad raster card (either is 9070), it's just one of those things that so many games really are going to tangibly have better perf/iq with one tier up (to 9070 xt/7900xtx)...the price difference is justified.
9070 is not incredibly dissimilar to 7900xt, and while both have their uses (for generally 1440p users), the small price difference to 9070xt (unlike the difference between 7900xt/xtx) makes them both look bad IMHO.
Especially if you tweak it. I think 9070/7900xt will fall into the 1080p/1440 up-scaling camp much earlier (and for some users already do fit that definition).

I understand this user is generally aiming for high FR in less-demanding titles, and in this instance 7900xt may be enough or potentially even slightly better in some raster situations (which is absolutely a fair point).
Especially considering the price (which is some cases is incredibly important; for this user they appear willing to spend the extra money if it's worth it, which it generally is imho).
9070 xt is such a great card for this target (1440p) market it's difficult not to rec to even these type, imo. And those negative differences in raster very small while the leads in other areas more important imo.

Never know when a newer game he plays might be built around similar standards as current AAA, even if to a lesser ratio (ie: they will run 120fps where AAA 60fps), in which 7900xt would then likely be at a deficit.

If really is just chasing frames at any cost, they should be looking at a 7900xtx. This is also sometimes where nVIDIA benefits, due to their cache/memory structure under a light load.
Depends on the title/how it was made if it benefits from the compute advantage or quick fetch more...it's really split, but oftentimes nVIDIA wins that battle (CS/Delta Force etc vs COD etc).
Perhaps for this particular and unique individual, even a lower-end nVIDIA card may work better for them (I am not familiar in performance in those titles). 9070 xt is just a great catch-all w/ few drawbacks.

I'm real big on "what will last the longest before a user finds a sitch they are unhappy with it/for the dollar". I don't think most will miss a few frames at 100+fps in *some* older/less-demanding situations.
They certainly will at <50/60/70/80 (depending on user). 7900xt is likely to encounter those problems earlier. Again, it doesn't make it a bad card (just like 9070), but they would need to be cheaper IMHO.
Or you would need to *know* you need that extra compute/buffer/bw (and *never* other arch benefits from RDNA4), and can't afford 9070xt. That's a very particular type, but this one appears able to swing it.

In an ideal world 9070 would be much cheaper, and the 7900xt/xtx (especially used) pricing would reflect the differences with the XT. Right now they don't. If/when they do, certainly buy those cards if right for you.

 

[AleXXX666]

For PSU any decent 850 W ATX 3.0 will do just fine. ATX 3.0 should deal with any GPU spikes really. I believe 9070XT doesn't exceed 400W in spikes anyway.
Peak power excursion (ATX 2.x)=100%
Peak power excursion (ATX 3.0)=200%

As future proof PSU, well, in EU electricity will not become cheaper so any system which can not be handled by a 850W PSU is counterproductive in costs IMO.

As for the card, 9070XT clearly, lower power means less heat inside the case and in your room also less noise.

Yeah. 4W difference is truly a BIG DEAL.

 

[hermesa]

For PSU any decent 850 W ATX 3.0 will do just fine. ATX 3.0 should deal with any GPU spikes really. I believe 9070XT doesn't exceed 400W in spikes anyway.
Peak power excursion (ATX 2.x)=100%
Peak power excursion (ATX 3.0)=200%

As future proof PSU, well, in EU electricity will not become cheaper so any system which can not be handled by a 850W PSU is counterproductive in costs IMO.

As for the card, 9070XT clearly, lower power means less heat inside the case and in your room also less noise.

I don't really care about heat since my case have super good airflow , 3x120 intake NZXT core fans from the fron of the case , 2 intake 2x140mm lian li intake on the bottom and 2 exhaust 120mm on top of the case( AiO radiator).The CPU isn't generating much heat since it's closed with AiO pump. The GPU right now is not reaching more than 55C during heavy gaming.There is literally no parts that generate much of a heat inside the case + even if there is some heat - the ariflow in that case is really really good.A new GPU won't break the '' idyllic'' temperatures that I have. The 150$ for that NZXT H6 flow case that I spent are my best well spent money for PC case ever. I plan to buy 3x120mm Lian li fans that comes with connector and like that I can put one more exhaust fan on the back of the case too. Even without it ,it's totally fine.

 

[Shou Miko]

@hermesa not to forget if you game some games in the near future will have RT as required/mandatory which will also lead to low performance on the 6000 series which was one of the reasons I actually plus stock issues I went with the Sapphire Radeon RX 9070 Pure Gaming OC instead of a RX 7900 XT I know it has lower vram but I do not want to suddenly be like a fine card with a good raster suddenly performance poorly or won't run a game because the developers things that RT is required or mandatory for their games.

Link: https://nerdburglars.net/question/w...-tracing-instead-of-offering-it-as-an-option/

I personally didn't want to find out a game I want to play suddenly ain't playable because a dev team decided that RT is required and FSR4 ain't released for the RX 7000 series to bring better performance and if FSR3 ain't on this game well it won't be a good experience.

 

[hermesa]

My 'short' suggestion is simply this:

1. Buy 9070 xt. Get your favorite assortment of stress tests ready. Or, you know, just play some games. BOLO any perf degradation (not just crashes) during the following.
2. Test memory limit (as this is the main constraint of almost every AMD GPU, this one included). I would start at 2700mhz; stay there if this 'not your thing', but more may help (~1-3% depending on model).
3. Lower voltage (uv/oc), testing thoroughly along the way. Perhaps start at ~ -40. This should raise the clock speed.
4. Lower power limit until performance is no longer acceptable to you, or it hits your personal goals for power consumption.

Voila', you've got about the best bang-for-buck you're going to get, along w/ decent power efficiency, which *should* (realistically) be enough for most peoples' scenarios.

If you can afford it, this is my suggestion to pretty much everyone right now. 4k may be fine for some games, 1440p for others, 1080p60 (1440p48 mins) for Wukong. Very nice place to be for the price IMHO.
Should last a very long time, and scale generations well (ie: when 1440p native is no longer acceptable for you, 1440p up-scaling should last a good long while).

I think as more people buy these and do this very thing (getting 100fps in Time Spy; something even the weakest model in W1zard's testing can do, even if not 'optimal' compute/bw) people will understand.
This card is exactly what the market and people needed (granted I'd always be happy if prices stabilized and it were generally cheaper). Tweaked power consumption (especially for the perf tier) is also very good.

The weird thing about 9070 xt is the stock bw that gives it a very weird look of wanting ~5-8% more perf (or better efficiency), but this is remedied if you're willing to take (varying amount of time) doing the above.
And really is quite an awesome card right now (for the price) if you're willing to do that IMHO.

I think there will be a lot of people pissed off to varying degrees when the next-gen (3nm?) low-end (think '600' level) performs similar (as that's where the market needs to be fairly-soon).

But you, you smart shopper, will be sitting just fine...arguably more ahead of the curve than *most* people, especially those with a similar budget right now. Not unlike a 4090 owner a tier above (at 4k).
Many that spent more aren't really going to 'get' more, realistically-speaking, and you can laugh about that too.

If I were the strange outlier of something like a 1440p 7900xtx owner, I'd be a little pissed off, but that's another story. That's also still not a 'bad' card for some people, just better longevity/utility if it had FSR4.
Ofc, 4090 owners have also been sleeping for over two years, but that's a different budget/perf requirement.

The only other option IMHO is buying/holding something to weather the storm until you can afford (when prices drop and/or a new gen with similar perf releases at lower prices) at least something similar.
Ofc, when prices stabalize and their relative (used) prices are worth it, which right now they generally are not imho. Hence 9070 xt becomes the go-to (if/when you can find one within your budget).

Honestly , the prices in Bulgaria are even more ridicilous than worldwide. The prices of 1080Ti were 400BGN(200$) until months ago. People here really like to exaggerate and overprice their gaming PC parts.

@hermesa not to forget if you game some games in the near future will have RT as required/mandatory which will also lead to low performance on the 6000 series which was one of the reasons I actually plus stock issues I went with the Sapphire Radeon RX 9070 Pure Gaming OC instead of a RX 7900 XT I know it has lower vram but I do not want to suddenly be like a fine card with a good raster suddenly performance poorly or won't run a game because the developers things that RT is required or mandatory for their games.

Link: https://nerdburglars.net/question/w...-tracing-instead-of-offering-it-as-an-option/

I personally didn't want to find out a game I want to play suddenly ain't playable because a dev team decided that RT is required and FSR4 ain't released for the RX 7000 series to bring better performance and if FSR3 ain't on this game well it won't be a good experience.

By the time this happens - I will be able to afford a new GPU and maybe I will be on a newer platform(I hope)

 

[Aken Bosch]

From a neighbor to another - I'd wait.

https://www.emag.ro/placa-video-xfx...16gb-gddr6-256-bit-rx-97tswf3b9/pd/DM4PPY3BM/ , one of the cheapest models, 800 EUR including VTA ( about 1600 BGN).

On the other hand, with the orangutan and his tariffs, who knows what's next in terms of pricing...

 

[AVATARAT]

At the higher power draw that is not undervolting it's just a overclocking (poor efficiency) that's way i don't like it.

For me UV is when lowering watts and at the same time not losing any performance RX 7900 XT just can't handle that....

OK.
Let's say that the card has a power limit (TDP) 300 W (345 W with +15%), when you reach it, your frequency/performance will be limited. When you undervolt, your card will use less watts so that will open up headroom for more watts so you can manually raise the GPU frequency to feed the opened PL so your performance will be increased in the end, that's the 7000 series way.
And yes, you can use less voltage for the same clock, otherwise undervolt simply will not work, and this is based on what quality your GPU is.

With the 9000 series, when you lower the voltage, the GPU will automatically increase its frequency to fill the new PL gap. But now we also have a frequency limit (probably anti-crash protection) , so it can't increase it too much. Yes, there is a slider through which we can control its frequency, but it is almost useless.

Whether you (we) like it or not doesn't matter, that's the way AMD CPU/GPUs (will) work (in the future).