What's the obsession with PSUs?

[ZenZimZaliben]

This may seem like a bad way to determine a good powersupply. Of course you read the specs. But the best way I have found to determine if a powersupply will be good or not is based off it's weight. If it says 700w and wieghs slightly more then a can of coke, more then likely it is crap. All of my powersupplies have been quaility, and you can tell they are quality because they are heavy. This comes from quality components, quality copper and lots of it, and nice large heatsinks. Basically the lighter the PowerSupply, the more junkier it is likely to be.

 

[Polarman]

Computer stores like to put "el cheapo" parts to build budget crap pc's. They'll put 10-15$ psu's in those rigs. They like doing this because they WANT you to have problems to return to the store frequently to make more $$ out of ignorant suckers that do not know that most of the time the real culprit is that cheapass psu.

I always tell people to get quality psu's but are too cheap themselves to buy a good one. Well F%$^ them. :shadedshu

I use a PC Power&Cooling Silencer 750W Quad (Red):

• 750W Continuous @ 40C (825W Peak)
• Up to 90% (10dB) Less Noise per Watt
• ATI Crossfire / Nvidia SLI Certified
• 80+ Certified (83%); .99 Active PFC
• +12VDC @ 60A (Powerful Single Rail)
• Rock-Solid, Super-Clean DC Output
• 24-pin, 8-pin*, 4-pin M/B Connectors
• Quad PCI-E and 15 Drive Connectors
• Automatic Fan Speed Control Circuit
• 5-Year Warranty and Tech Support

This thing is rules.

 

[thebluebumblebee]

PC Power & Cooling

 

[enaher]

To me the obsession for a good to great PSU choice over the average is very comaparable to auto insurance. You may never use it, but you still pay through the teeth to have the peace of mind that if something does go wrong, you are covered.

I totally agree, to each there needs but if im spemding 1000$ on a PC, spending 150$ on a good psu shouldnt be a issue...

PCP&C FTW

 

[Flyordie]

The True PC Enthusiasts Power Supply Brand. ;-)
Oh and... pretty much all the power you will ever need. (for the PSU in the pic)

 

[MKmods]

I don't care what anyone says. I will never skimp on the PSU in any system I'll ever build.

+1!

 

[FordGT90Concept]

That just means it won't fail after 5 years, It will become less efficient over time and the max output will probably fall in turn

One of the 620w PSUs already died. It was replaced under Enermax's warranty. Now I have a new one and it still has 3 years of warranty left on it. If it dies during the last two years, the extended warranty pays for itself and then some (about $110 saved). If it doesn't die during the warranty, I only lost $40.

 

[AsRock]

I doubt it, from the power equation P=IV (current x voltage) that would equal 216w just for a 7600gt and 360w for the 2900xt!!!!

{Edit] i forgot those are old cards and probably running on the 5v line - still 30A x 5V = 150w for an old graphics card.

A overclocked 2900XT including the rest of the system can take around 380w. Don't know about a 7600 but a 7900GTOCSC is around 240 tops in my system.

Depends on what games you play too and how many items you have booting up when you turn your system on.

Games like NWN2 in area's took more power than most other games i know and only one other i know of and that was Crysis at the time.

Games like TW 08 COH take push my current system around 280w-310w. BUT NWN2 and Crysis with push it to about 340w-350w which is the sweet spot for my PSU.

Armed Assault though is strange as it needs high shaders and fast CPU to run better but only takes a little more than (10w-15)w what COH or TW 08 takes. Even though the detail levels and AA AF res are bumped right up with at least 3000m view distance.

I got my PC&Power due to it's high efficiency around the 350w marker and after all better having to much power than not enough ( with in reason of course ).

 

[iandh]

I don't understand why people are giving advice to other members to buy 750w PSU's when the person's rig would only use 400w max. They don't even consider the other aspects you have to consider when buying a PSU.

Well, there are two good reasons, although I've heard many bad ones:

1) Most PSU's hit their peak efficiency at anywhere from 30-70% of their max load rating, so that would be the 400w on 750w PSU you speak of. Assuming prices are all similar, it is good to tune your PSU's peak efficiency point to your average load draw. Not all PSU's are like this, but most are. Any good PSU review will show load vs. efficiency charts, and sometimes there can be quite a large difference, such as 87.5% @ 350w and 81% @ 750w

2) As a person who manufactures electronics for a living, and has lots of experience in transformers and amplifiers, I can wholeheartedly say it is much better for the PSU, and much better for your computer to not be running your PSU to the bleeding edge. Only the very best PSU's are able to run at 100% load and not have their lifetime adversely affected. Your power will be more stable, which can make for a more stable system, especially at OC, and your PSU will lead a happy and stress free life.




In general, based on experiences in my career, I think it is wise to run a PSU rated to at least 20% more than your actual load. Going beyond 50% can actually be bad though because you start to drop below the efficiency peak, but this really depends on PSU. For instance, at work, if I have a component that draws 6A @ 24v, then I will typically purchase a 10A switching power supply for the sake of reliability.

 

[n-ster]

Well, there are two good reasons, although I've heard many bad ones:

1) Most PSU's hit their peak efficiency at anywhere from 30-70% of their max load rating, so that would be the 400w on 750w PSU you speak of. Assuming prices are all similar, it is good to tune your PSU's peak efficiency point to your average load draw. Not all PSU's are like this, but most are. Any good PSU review will show load vs. efficiency charts, and sometimes there can be quite a large difference, such as 87.5% @ 350w and 81% @ 750w

2) As a person who manufactures electronics for a living, and has lots of experience in transformers and amplifiers, I can wholeheartedly say it is much better for the PSU, and much better for your computer to not be running your PSU to the bleeding edge. Only the very best PSU's are able to run at 100% load and not have their lifetime adversely affected. Your power will be more stable, which can make for a more stable system, especially at OC, and your PSU will lead a happy and stress free life.




In general, based on experiences in my career, I think it is wise to run a PSU rated to at least 20% more than your actual load. Going beyond 50% can actually be bad though because you start to drop below the efficiency peak, but this really depends on PSU. For instance, at work, if I have a component that draws 6A @ 24v, then I will typically purchase a 10A switching power supply for the sake of reliability.

Valuable info right here guys!

 

[Flyordie]

snip

100% correct. However...
Some companies design their PSUs for sustained output like Seasonic or Sventeam.
Seasonic overspecs their PSUs by 20-25% on the S12 series and 25-33% on their S12 II series.
Sventeam did a standard 20% across the board if the reseller wanted it... but idk how they do it now.

 

[TheMailMan78]

Like Shadow said I never skimp on the PSU. Hell I use a 750 watt Corsair in my rig and I've yet to strain it. Better safe than sorry.

 

[Flyordie]

Like Shadow said I never skimp on the PSU. Hell I use a 750 watt Corsair in my rig and I've yet to strain it. Better safe than sorry.

My EA380 could easily handle 420-440W. (despite it being a 380W PSU)

 

[silkstone]

To me the obsession for a good to great PSU choice over the average is very comaparable to auto insurance. You may never use it, but you still pay through the teeth to have the peace of mind that if something does go wrong, you are covered.

It is an investment to the safety of your parts. you can get an avg. PSU ( Liability insurance), and when something goes wrong, you have to pay out of packet for the damages. Where with the better quality PSU's ( full coverage) the accidents shouldnt happen.

This doesnt mean there wont be a failure of the PSU, but your chances of PSU related issues drop drastically when running the correct PSU for the application versus one that just gets the job done.

Nice simile, i'm beginning to understand your way of thinking now. But still that doesn't apply to everyone. Keeping with the theme, you wouldn't reccommend someone getting a $5,000 a year insurance policy on a $5,000 car.

In general, based on experiences in my career, I think it is wise to run a PSU rated to at least 20% more than your actual load. Going beyond 50% can actually be bad though because you start to drop below the efficiency peak, but this really depends on PSU. For instance, at work, if I have a component that draws 6A @ 24v, then I will typically purchase a 10A switching power supply for the sake of reliability.

That was my point. The majority how PSU have the highest efficiency at somewhere between 70-80% load, although i agree some may have highest efficency at 30% load but they are less common.

Buying a 700w PSU for a system that only uses 400 watts max would mean that the PSU is only working at 70% max and so very efficient. But most of the time the computer would only be using 150-200w, so what's that, 20% load? now that isn't very efficient. in that scenario a 550w psu would be much better suited, and even if the person wanted to upgrade later there would still be enough power left for xfire.

 

[Flyordie]

Thats why Active PFC is around.

 

[largon]

Active (nor passive) PFC does not increase PSU efficiency. Infact, PFC circuit consumes power so it actually lowers the efficiency of a PSU.

 

[phanbuey]

The point is... if you're building a PC you want to have flexibility. What if the GT300 comes out and its priced at $300 and its 3x faster than everything else, but draws 350W just by its lonesome...

and a while ago you decided you would NEVER need more than 550W (like I have done). Well, you're not getting that GT300 then unless you also buy a new PSU. So instead of spending the original $109.99 to get that 750W, you're now gonna have to sell your used $69 PSU for $40 somewhere and buy the $109.99 PSU anyways, and now you're out $30 bucks (and its a pain in the butt).

By imposing an artificial limit on your PSU "because it isnt what you need now" you hurt yourself later on.

High end hardware is drawing more and more power.... and will continue to do so. Dual GPU cards... monster single GPU cards... CPU's with 8+ cores on them. I remember people saying 500W!?!?! you'll NEVER need that much power.

 

[silkstone]

The point is... if you're building a PC you want to have flexibility. What if the GT300 comes out and its priced at $300 and its 3x faster than everything else, but draws 350W just by its lonesome...

and a while ago you decided you would NEVER need more than 550W. Well, you're not getting that GT300 then unless you also buy a new PSU. So instead of spending the original $109.99 to get that 750W, you're now gonna have to sell your used $69 PSU for $40 somewhere and buy the $109.99 PSU anyways, and now you're out $30 bucks (and its a pain in the butt).

By imposing an artificial limit on your PSU "because it isnt what you need now" you hurt yourself later on.

High end hardware is drawing more and more power.... and will continue to do so. Dual GPU cards... monster single GPU cards... CPU's with 8+ cores on them. I remember people saying 500W!?!?! you'll NEVER need that much power.

If you bought that 750w psu a few years ago you'd still might need to upgrade your PSU anyway. It'd originally have maybe 450w on the 12v rails and 150-200w on the 5v line. The rated output of psu's degrades at about 10% a year depending on usege, the capacitors age or "dry up". So say you've had it for 3 years, 450w on the 12v line minus 30%, you're looking at having only somewhere around 350w left.

One thing people forget is that PSU's age! you should upgrade your psu every 2 or 3 years. So buy one that will last you 3 years most. there is no point getting a 1000w psu and expecting it to still be good 5 years later, at the point when you might actually need a 1000w PSU.

 

[Flyordie]

hmm...
PII= 108W
HD4850-110W
Mainboard-30W
DRAM- 20W
HDDs- 15W
1 Fan-10W
Optical Drive- 15W
Sooo...
308W if EVERYTHING IN THE PC is at 100% usage... which is rare.... Typical usage =
190-200W for this system and I should know... the Kill-A-Watt says 193-195 while playing STALKER:CS. So, why do people really say such things... Its not like I am gonna have a 200W i7 and 20 HDDs and 2x HD4870s. For the system in my specs.. what would you recommend?

 

[phanbuey]

hmm...
PII= 108W
HD4850-110W
Mainboard-30W
DRAM- 20W
HDDs- 15W
1 Fan-10W
Optical Drive- 15W
Sooo...
308W if EVERYTHING IN THE PC is at 100% usage... which is rare.... Typical usage =
190-200W for this system and I should know... the Kill-A-Watt says 193-195 while playing STALKER:CS. So, why do people really say such things... Its not like I am gonna have a 200W i7 and 20 HDDs and 2x HD4870s. For the system in my specs.. what would you recommend?

300W - most PSU's can handle 8W over rated output.

 

[silkstone]

300W - most PSU's can handle 8W over rated output.

It depends, some can handle 10% over rated but others handle much lower. For every 1 degree C over the 25C operating temp the power supply generally looses 3W of its rated output. Also the load on his system won;t be evenly distributed over the rails, most of it would come from the 12v rails.
So you'd need AT LEAST 300w over 2 12v rails. you'd be looking at a 450-550w PSU. If you want to go xfire in the future you'd need a 600-750w PSU

 

[largon]

300W PSU for 200-300W load?
Just make sure you have ear muffs at hand.

 

[iandh]

300W PSU for 200-300W load?
Just make sure you have ear muffs at hand.

And a fire extinguisher

 

[phanbuey]

naaAah itll be fine.

you'd probably have enough left over for that USB coffee warmer you've always wanted.

 

[n-ster]

The new HX 750 and 850 seem promising