Need advice...SLI GTX 970 with 3.5 GB VRAM Issue or one R295X2

[newtekie1]

Hope this helps- 970 will only be constantly playable up to 3.5GB RAM usage. That's a fact.

I will list my user case below on 2x CFX 290x
Far Cry 3, 4k, 4x MSAA- playable with 6000MB VRAM + 400MB dynamic usage shown in GPU-Z (it shows double the amount used due to 2x cards involved)
Becomes unplayable during map loading (in game) where VRAM goes to 7500MB+ and dynamic about 800MB (total exceeding 8GB VRAM or 4GB per card).

Skyrim no mods, 4k, no MSAA- playable with 4600MB + 400MB dynamic.
Becomes unplayable with 4x MSAA with 5600MB

What this might show is that there may be slightly less RAM available to me for Far Cry 3 map loading and a lot less processing power for doing 4x MSAA on Skyrim.

For 1440p what you actually need is a 980 Classified or similar highly clocked version for some future proofing.

If you want to be limited by GPU processing only in the future, then you need 2x 8GB 290x.

Why are you thinking the RAM doubling applies to 290X Crossfire but not the 970s in SLI? Also, amount of RAM used doesn't double like that in GPU-Z either. GPU-Z show the amount of RAM used per card, the card you have select at the bottom.

If anything, if you theory was correct, the 970s would be usable up to 7GB.

But what you are seeing is in FC3 you're going way over your available RAM and the card is beginning to use system memory. You can kind of think of the extra 0.5GB on the 970 a buffer to it doesn't have to use system memory when it goes over 3.5GB. Using the 0.5GB is still a lot faster than going out and using the system memory. Either way, both cards(290X and 970) are going to have to use system RAM. The same goes for Skyrim. The reason FC3 is more playable with more system RAM is that FC3 is a much more optimized engine than Skyrim. That is why you can have 2GB of system RAM used with FX3 and the game is still playable. But with Skyrim it becomes unplayable whenever it goes over 1GB of system RAM used.

 

[Ominence]

Why are you thinking the RAM doubling applies to 290X Crossfire but not the 970s in SLI? (I didn't say SLI and agree that it's irrelevant to the OP's SLI setup )

If anything, if you theory was correct, the 970s would be usable up to 7GB. (this is true personally speaking)

Also, amount of RAM used doesn't double like that in GPU-Z either. GPU-Z show the amount of RAM used per card, the card you have select at the bottom. (what was said is based on observations only. When I disable CFX the RAM usage counter halves. With CFX on, the memory thingy is only available on the 1st card and it shows double to against CFX disabled)

 

[shoti02]

wait a Minute....far cry 3 is unplayable when it went to 7500 mb....but this is not much more then the gtx 970 .....the gtx is good till 3500 mb ( doubled at the Radeon )......or am i wrong ??

 

[Ominence]

But what you are seeing is in FC3 you're going way over your available RAM and the card is beginning to use system memory. You can kind of think of the extra 0.5GB on the 970 a buffer to it doesn't have to use system memory when it goes over 3.5GB. Using the 0.5GB is still a lot faster than going out and using the system memory. Either way, both cards(290X and 970) are going to have to use system RAM. The same goes for Skyrim. The reason FC3 is more playable with more system RAM is that FC3 is a much more optimized engine than Skyrim. That is why you can have 2GB of system RAM used with FX3 and the game is still playable. But with Skyrim it becomes unplayable whenever it goes over 1GB of system RAM used.

Thanks, I'm not too fussed about memory usage. I know when FC3 drops to a slideshow (for 2-3 secs during map loading) is when it goes to DRAM and beyond VRAM. I also believe if I had 8GB, it wouldn't be an issue. I have 32GB DRAM and no page filing.
I know I don't have enough GPU processing for Skyrim. It's fairly constant between no AA and 4x AA. For that reason I believe (possibly incorrectly) that RAM is not being exceeded with Skyrim.

I also game without vsync so changes and stutters are very noticeable when they do happen...also the inevitable screen tearing!!

 

[Ominence]

the gtx is good till 3500 mb ( doubled at the Radeon )......or am i wrong ??

I am sorry, based on by experience with GPU-Z memory counter, I believe that single GTX will be good till 3.5GB and SLI up to 7GB.

Also remember, my FC3 setting is UHD (3840x2160) with 4xMSAA and everything maxed out.

 

[shoti02]

...the final question is, will i get a benefit from the 4 GB fully accessable ram of the Radeon ?.....are their any other issues ??? the gtx is a newer Modell but does it make a difference ??

 

[TRWOV]

For 1440p I don't think you'd have a problem with the 970s. Only concern would be resale value due to the drama.

 

[Ominence]

wait a Minute....far cry 3 is unplayable when it went to 7500 mb....but this is not much more then the gtx 970 .....

note below
Becomes unplayable during map loading (in game) where VRAM goes to 7500MB+ and dynamic about 800MB (total exceeding 8GB VRAM or 4GB per card).

...the final question is, will i get a benefit from the 4 GB fully accessable ram of the Radeon ?.....are their any other issues ???

at 1440p perhaps not with a single card and more power and heat to deal with. With CFX even more power and heat to deal with and you will get the benefit in some very specific scenarios only depending how good the scaling is. I find that scaling has improved immensely with XDMA as long as you keep the drivers updated. Tread carefully!

but again since at 1440 you will not be pushing the limits too much, the 970 SLI might still be ok for the time being till the next gen is out. if you're gonna lose money on the 970 SLI (I know you said full refund), I wouldn't bother. For the full refund option though, get the cheapest 980 SLI setup you can get (within 800 euro if possible). If outside budget (800), then get the best 290x CFX deal you can get (custom cooler) or the 295x2. implement the power flyer fully if/when you get the 295x2.

 

[shoti02]

....u haven´t read the full post.....i am talking about a r295x2..it is watercooled !! ( so no issues about heat an noise ) my psu is big enough ( supernova 1000W )...

 

[Ominence]

....u haven´t read the full post.....

read edited response.

hope the below helps further

usable RAM and related performance hit 295x2 > 970 SLI
Power consumption, heat 970 SLI > 295x2
Overclocking ability 970 SLI > 295x2
overall performance potential @ 1440p 970 SLI > 295x2

 

[shoti02]

i think i go with the 295x2....all the night i read the Internet and in my opinion is the package from the 295 better then sli 970....in Germany it is 06.02 am.......and i am totally stressed because the decision

 

[Caring1]

....u haven´t read the full post.....i am talking about a r295x2..it is watercooled !! ( so no issues about heat an noise ) my psu is big enough ( supernova 1000W )...

Good luck with that, from the reviews I have read it needed to be water cooled because it ran so hot and still does.
Another factor to consider is the amount of power it uses and your power bills.

 

[Ominence]

you won't be disappointed- it's a good AMD flagship.

do consider the available options between 2x 290x and the 295x2.

In all honesty though CFX requires water cooling (mine is, runs 30C above ambient @ 7.5% OC and +50% power target) for maintaining clock speed and managing fan speed but if you can water cool separate PCBs then the power circuitry constraints on the 295x2 (apart from the PSU requirements) will not apply.

 

[Ominence]

Good luck with that, from the reviews I have read it needed to be water cooled because it ran so hot and still does.
Another factor to consider is the amount of power it uses and your power bills.

it's designed to run that without down clocking around 40C, though I would have some concerns about the VRM temps if I was sitting in a room that hot! AMD themselves are very clear about the power requirements. The 500W power is also well known.

 

[newtekie1]

You also have to remember that the 295x2 throttles way before the 290X does. The 290X starts to throttle at 90°C, the 295x2 throttles at 72°C. So AMD had to make the thing loud. At idle the stock fan on the 295 is louder than the 970s at load. And at load it is over twice as load as any 970. Plus, there are reports of even with the watercooling solution, the 295 still throttles and performance drops.

 

[Ominence]

You also have to remember that the 295x2 throttles way before the 290X does. The 290X starts to throttle at 90°C, the 295x2 throttles at 72°C. So AMD had to make the thing loud. At idle the stock fan on the 295 is louder than the 970s at load. And at load it is over twice as load as any 970. Plus, there are reports of even with the watercooling solution, the 295 still throttles and performance drops.

I think the throttle down and fan noise has more to do with the VRM circuitry fan on the card itself- it is packaging constrained and heat dissipation does suffer as a result. When it gets to the tmax, it down clocks and makes whatever noise it has to at that level. The VRM is air cooled only. check the long thermal pads in the middle- effective contact area issue.
I think the GPU temp and radiator fan still remain manageable for temp and noise.

 

[Caring1]

Thanks for those pics, very interesting.
I'm thinking the Asetek pumps could have been smaller to allow for better air flow, and two radiators can be used to aide cooling even more. Those pumps look to be a standard size like the ones they make for CPU's.
I wouldn't mind seeing one of these beasts modified.

 

[Ominence]

I'm not sure if anyone has modified them but there are separate full cover, single slot blocks available from EK and others. But that's off budget and off topic and the VFM equation doesn't measure up for further modifications!

Although it's supplied as a single rad/fan setup, a 2nd fan can also be used for push-pull config, which would make the heat dissipation better on the GPUs, possibly with lower noise. That would depending on the ratings of the fans though. Need Noctua or Noise Blocker for that.

I would remove the fan and shroud altogether and get a larger fan to blow close to it somehow. it's a pity they kept it 2 slot because otherwise if could have had a much taller and possibly wider copper fin stack that wouldn't retain so much heat.

 

[newtekie1]

I think the throttle down and fan noise has more to do with the VRM circuitry fan on the card itself- it is packaging constrained and heat dissipation does suffer as a result. When it gets to the tmax, it down clocks and makes whatever noise it has to at that level. The VRM is air cooled only. check the long thermal pads in the middle- effective contact area issue.
I think the GPU temp and radiator fan still remain manageable for temp and noise.

I think it is both. As the GPUs get hotter they draw more power(this is a basic rule for circuitry). The VRM is definitely weaker on the 295 than on two 290Xs, it can't take the same power draw as two 290X cards could. The 295 I had would start to throttle after about 10 minutes of heavy gameplay in a closed case(Corsair 650D). Once the temp hit 72°C on the GPUs the clocks started to drop. It managed to not throttle in an open test bench, but I don't think there are many(if any) cases that can keep the 295 under 72°C without sounding like a jet taking off. The noise didn't really bother me, I always use headphones, but the throttling did. I even tried to flip the fan around to pull cool air in through the GPU's rad, and that extended the time before the card started to throttle. But it would still start to throttle after 20-30 minutes of gaming.

Yeah, if you have a low ambient temp in your room you might get lucky and get minimal throttling, but heck this card puts out so much heat it actually upped the temp of my room by a good 5°F. The A/C was keeping the room at ~70°C, after about half an hour of gaming the temp in the room was up to 75°F.

 

[Ominence]

I think it is both. As the GPUs get hotter they draw more power(this is a basic rule for circuitry). The VRM is definitely weaker on the 295 than on two 290Xs, it can't take the same power draw as two 290X cards could. The 295 I had would start to throttle after about 10 minutes of heavy gameplay in a closed case(Corsair 650D). Once the temp hit 72°C on the GPUs the clocks started to drop. It managed to not throttle in an open test bench, but I don't think there are many(if any) cases that can keep the 295 under 72°C without sounding like a jet taking off. The noise didn't really bother me, I always use headphones, but the throttling did. I even tried to flip the fan around to pull cool air in through the GPU's rad, and that extended the time before the card started to throttle. But it would still start to throttle after 20-30 minutes of gaming.

Yeah, if you have a low ambient temp in your room you might get lucky and get minimal throttling, but heck this card puts out so much heat it actually upped the temp of my room by a good 5°F. The A/C was keeping the room at ~70°C, after about half an hour of gaming the temp in the room was up to 75°F.

My open air 4x CFX 7970GHz Gigabyte 3x Windforce throttled down card 1 and 2 all the time in an open case. That was an instant giveaway of how good multi-card scaling was (for >2 cards) and I knew my setup had to be fully WCed. Went with water on my 7970 then these 290Xs. My desktop is never going to move so I have a 3x3 140mm rad some distance away with the GPUs/CPU/MB on water. The 290Xs cannot put up a fight with that much water to keep them cool

 

[shoti02]

thnx for the replies....i slept very uncomfortable.....get up for 10 minutes......i thought that the r295x2 ( what is ALWAYS watercooled ) is not as loud as two gtx in sli ??? now i am confused

 

[Ominence]

I won't comment on the noise as I haven't used it- check reviews for that. What I will say is, that at a user level, the issue with the 970 which you are concerned with, cannot be fixed. However, the 295x2 heat and noise can be managed.

The 295x2 is a hybrid cooling solution.
GPU core is water cooled (water block, integrated pumps, fan and rad)
VRM and VRAM is air cooled (finned heat spreader, fin stack heat sink and fan)

If you want proper fully water cooled 295x2 you need something like this- all for additional cost obviously and no warranty. You could also consider the ASUS Ares III.

http://www.ekwb.com/shop/ek-fc-r9-295x2.html

Alternatively consider custom cooled 290Xs like the 970 SLI you have now. Make sure you have 1 extra slot between the cards. If you install on the 1st slot then the 2nd card should only go in the 4 slot spacing. Slot 1 has card 1, 2nd covered by cooler, 3rd slot space left empty (may not have a slot at all depending on MB- just need the spacing), 4th slot card 2.

 

[shoti02]

i have the asus maximus hero VII...there ist not much space between Slot 1 and Slot 2

i know , water cooiling is nice...had done for a couple of years...also i had made my own ..( the site was www.hart.core.de is not more online ) ...it is quite cool but it is very expensive and with the next gen u can throw away the water block.....watercooling is cool...and the optic is awsome....

 

[Ominence]

i have the asus maximus hero VII...there ist not much space between Slot 1 and Slot 2

The spacing on the VII Hero is spot on. The red PCI-E slots are at position 1 and 4 in reference to each other.
Stay sensible on cost and get custom 290Xs, 4GB or 8GB- the choice is yours. Given how concerned you are with the SLI 970s, I'd go with the 8GB option if you can afford. It is not required/necessary however.

 

[newtekie1]

thnx for the replies....i slept very uncomfortable.....get up for 10 minutes......i thought that the r295x2 ( what is ALWAYS watercooled ) is not as loud as two gtx in sli ??? now i am confused

Oh no, the 295 is way louder than two GTX 970s in SLI, especially at idle(since most aftermarket 970s turn the fans completely off at idle making them 100% silent). If it was custom watercooled it could be quieter, but the stock AIO watercooler isn't up to the task of cooling the card card properly so the fans have to really work, which makes them loud.

You might be able to lower the idle fan noise with a custom fan curve through overclocking software, but that just means the GPUs will idle hotter, which means the card will start to throttle sooner when gaming.