What PS?

[KyleGates]

Looking for reccomendations on a power supply for a system with two 8800GTX's. So far I have looked at THIS but then I was told that it absolutly SUCKED.

Then I heard THIS ONE might be aight, but not so sure on a BFG power supply.

And finally there was THIS but some of the reviewers were less than thrilled.

Isn't there a reasonably priced PS out there that will do two 8800GTX's well? (and if so...please point the way!)

 

[caberguy]

The Thermaltake would be fine... check out Jonnyguru's review of the 750W version... http://www.jonnyguru.com/review_details.php?id=17
The toughpower series is solid.

Or.... http://www.newegg.com/Product/Product.asp?Item=N82E16817342009 Topower is an OEM manufacturer for lots of other PSUs

 

[Corporate Thug]

http://www.newegg.com/Product/Product.asp?Item=N82E16817703006

I think the 1000w is overkill...

 

[KyleGates]

Originally posted by: Corporate Thug
http://www.newegg.com/Product/Product.asp?Item=N82E16817703006

I think the 1000w is overkill...

Even for dual 8800GTX's?
I plan to do ZERO OC'in but i want rock solid stability.

(Other specs: E6600, 4gigs Ballistix DDR800, 1 HDD)

 

[KyleGates]

Originally posted by: caberguy
The Thermaltake would be fine... check out Jonnyguru's review of the 750W version... http://www.jonnyguru.com/review_details.php?id=17
The toughpower series is solid.

Or.... http://www.newegg.com/Product/Product.asp?Item=N82E16817342009 Topower is an OEM manufacturer for lots of other PSUs

Talk about a THROUGH PS review! I had never even herad of jonnyguru but the dude sure did a nice review. I just want to make sure that what I get is gonna take dual 8800's with NO troubles.

 

[alimoalem]

the 8800GTX's may be power hungry but a decent 600-700w psu is fine. Anand's review has the entire system's power draw at 300w with a single 8800GTX...i really doubt a second one will get it over 550w (but always good to be safe, hence the extra 50-150w). in no particular order, i think the following would all be fine:

PC P&C 610w
Enermax liberty 620w
Silverstone 750w
Thermaltake750w
Corsair HX620w

there's this fortron (FSP) power supply going for $200 that says 1000w total...700w +300w GPU power supply (http://www.newegg.com/Product/Product.asp?Item=N82E16817104024) anyone know anything about it?

the PC P&C has 59A on the 12V rail, iirc; the enermax has 22A on each rail; the last three have 18A on each rail. i think the last 3 may push it a bit but the first two should certainly be enough, especially the first one

 

[Operandi]

When Daily Tech tested the 8800GTX with a quad core Intel CPU system it drew roughly 320 watts from the wall under full load.

If you figure that a single 8800GTX alone draws 150 watts that would still put the system well under 500 watts for total power draw.

If I were building it I would go with the 600 watt Seasonic S12 or M12.

 

[brikis98]

get either the PC Power & Cooling 610, PC Power & Cooling Silencer 750 or the Seasonic M12 SS-600. All are top of the line PSU's that should power your rig w/o issues.

 

[JAG87]

to be safe for an 8800 GTX SLI setup you need a power supply with a total combined power of 60A on the 12V rail/s.

anything less will cause you problems.



edited for spelling

 

[Operandi]

Originally posted by: JAG87
to be safe for an 8800 GTX SLI setup you need a power supply with a total combined power of 60A on the 12V rail/s.

anything less will cause you problems.



edited for spelling

No you don't.

 

[myocardia]

Originally posted by: Operandi

Originally posted by: JAG87
to be safe for an 8800 GTX SLI setup you need a power supply with a total combined power of 60A on the 12V rail/s.

anything less will cause you problems.


edited for spelling

No you don't.

Actually, that's a pretty good estimate. When my 500 watt Enermax Liberty wouldn't run my non-overclocked X2 4400 plus my non-overclocked 256MB X1900XT, I did a little research, and found out that they each draw more than 32 amps from the 12v rail. And since an 8800 draws more power than an X1900XTX, 60A on the 12v is about right, for two 8800GTX's.

 

[brikis98]

Originally posted by: myocardia

Originally posted by: Operandi

Originally posted by: JAG87
to be safe for an 8800 GTX SLI setup you need a power supply with a total combined power of 60A on the 12V rail/s.

anything less will cause you problems.


edited for spelling

No you don't.

Actually, that's a pretty good estimate. When my 500 watt Enermax Liberty wouldn't run my non-overclocked X2 4400 plus my non-overclocked 256MB X1900XT, I did a little research, and found out that they each draw more than 32 amps from the 12v rail. And since an 8800 draws more power than an X1900XTX, 60A on the 12v is about right, for two 8800GTX's.

wow, that's a ridiculous overestimate.

the absolute max that a single 8800gtx can draw from the +12v rail is 225W. That's because it can get up to 75W from the PCI-E slot and up to 75W from each of the 6 pin PCI-E connectors from the PSU. 75W x 3 = 225W. This corresponds to 225W/12V = 18.75A at the ABSOLUTE MAX.

lots of sites show that an entire system with a single 8800gtx under load pulls around 320W. Assuming this is all on the +12V rail (which it's not) and assuming it's all from the GPU (which it's definitely not), that's 26A. Add to that a second 8800gtx pulling (as i showed above) the theoretical max of 18.75A more, and you get a total of about 45A.

realistically, each 8800gtx won't pull anywhere near 18.75A and the 45A figure i calculated above is MUCH more than the max value under load. any reliable PSU with 40A total on the +12V rail(s) will be MORE than enough and i'd guess a high quality PSU with 30-35A on the +12v rail(s) will do the job as well.

EDIT: forgot to mention that if you have a low quality or unreliable PSU, this may not be the case. crappy PSU's are known to have large voltage drops when placed under heavy loads, which means that your +12v rail will actually be fluctuating at around ~11v, which is unacceptable for stability and normal operation. therefore, the numbers above apply to reliable (Seasonic, PC Power & Cooling, Enhance, etc) PSU's that work properly under stress.

 

[JAG87]

ROFL you do that
and let us know how it goes

40 amps on the 12V. lmao. you do know that your VGA is not the only thing that uses 12V right? your CPU does too. So hmm lets see 25A (300W) for one VGA, 25A (300W) for the second one, and 10A (100W) for an overclocked C2D = 60A

at this point if you have a 60A 12V PSU you cant even upgrade to a C2Q because the TDP is 130W and overclocked will probably absorb something like 150-200W. which implies another PSU upgrade.

Nice going brikis98...

 

[CairnGorm]

I talked with eVGA about it a couple weeks ago and here was their reply:


With a standard system, 750w should be enough, but you should be more
concerned with the +12v rail. If that will not push more than 28amps or
so (total), you may possibly run into issues with these cards in SLI on
top of several HDDs in RAID along with the rest of a standard system
configuration. Make sure your power supply is solid and over 34amps
total on the +12v rail and you'll be a happier man for doing so.

 

[JAG87]

and also, if my figure of 300W seems to unrealistic for an 8800 GTX, well since 225W is the absolute max, I wouldn't run those cards without having 250W of power available to each card.

Im just putting 300W down in case R600 sucks a bit more than an 8800 GTX. and in case you want to get a pair of those in future.

you know, just so you dont have to change PSU every friggen year.

60A is a very good figure for an 8800 GTX SLI rig. technically 40A will be dedicated to VGA, 10A to CPU, and the other 10A are HD, burner, fans, lights, dildos, vibrators. and for upgrading.

 

[Tegeril]

Originally posted by: JAG87
ROFL you do that
and let us know how it goes

40 amps on the 12V. lmao. you do know that your VGA is not the only thing that uses 12V right? your CPU does too. So hmm lets see 25A (300W) for one VGA, 25A (300W) for the second one, and 10A (100W) for an overclocked C2D = 60A

at this point if you have a 60A 12V PSU you cant even upgrade to a C2Q because the TDP is 130W and overclocked will probably absorb something like 150-200W. which implies another PSU upgrade.

Nice going brikis98...

[edit]Ah, you responded before I hit post, heh.

Except that it is 18.75A (225W) + 18.75A (225W), and 10A (100W), 47.5A.

 

[Corporate Thug]

Originally posted by: KyleGates

Originally posted by: Corporate Thug
http://www.newegg.com/Product/Product.asp?Item=N82E16817703006

I think the 1000w is overkill...

Even for dual 8800GTX's?
I plan to do ZERO OC'in but i want rock solid stability.

(Other specs: E6600, 4gigs Ballistix DDR800, 1 HDD)

750w is fine...

 

[brikis98]

Originally posted by: JAG87
ROFL you do that
and let us know how it goes

40 amps on the 12V. lmao. you do know that your VGA is not the only thing that uses 12V right? your CPU does too. So hmm lets see 25A (300W) for one VGA, 25A (300W) for the second one, and 10A (100W) for an overclocked C2D = 60A

at this point if you have a 60A 12V PSU you cant even upgrade to a C2Q because the TDP is 130W and overclocked will probably absorb something like 150-200W. which implies another PSU upgrade.

Nice going brikis98...

yes, i'm very well aware that the CPU is also on the +12v rail. yet despite that, actual tests (here's another one) show that a single 8800gtx system under load uses about 300W. that's the entire SYSTEM, including everything on the +12V rail, which means the 8800gtx itself pulls no where near 300W. i already explained above that it's impossible for a single 8800gtx to use more than 225W, and nvidia's own specifications quoted/graphed here state that they use no more than 150W each.

i believe nvidia also stated the following:

Geforce 8800GTX SLI: 680W with 40A on the +12V rail (dual +12V rails and SLI certification recommended)

and if you know anything about these recommendations, they are always over-estimates to take into account low quality PSU's that buckle and have massive voltage drops when under heavy load. therefore, i state again: a high quality PSU w/ 40A on the +12V rail will work just fine for an 8800gtx sli setup.

 

[brikis98]

Originally posted by: JAG87
and also, if my figure of 300W seems to unrealistic for an 8800 GTX, well since 225W is the absolute max, I wouldn't run those cards without having 250W of power available to each card.

Im just putting 300W down in case R600 sucks a bit more than an 8800 GTX. and in case you want to get a pair of those in future.

you know, just so you dont have to change PSU every friggen year.

60A is a very good figure for an 8800 GTX SLI rig. technically 40A will be dedicated to VGA, 10A to CPU, and the other 10A are HD, burner, fans, lights, dildos, vibrators. and for upgrading.

incidentally, i'm arguing what the minimum (safe) requirements are for a PSU for the setup he mentioned and NOT what PSU the op should get to future proof his system just in case he later on decides to go for two cards that might drain more power, maybe a quad core CPU and, you know, just in case he wants to power his whole house with it too.

 

[myocardia]

Originally posted by: brikis98
i believe nvidia also stated the following:

Geforce 8800GTX SLI: 680W with 40A on the +12V rail (dual +12V rails and SLI certification recommended)

and if you know anything about these recommendations, they are always over-estimates to take into account low quality PSU's that buckle and have massive voltage drops when under heavy load. therefore, i state again: a high quality PSU w/ 40A on the +12V rail will work just fine for an 8800gtx sli setup.

Hmm, you have a horrible memory, I guess:

Originally posted by: brikis98
and i'd guess a high quality PSU with 30-35A on the +12v rail(s) will do the job as well.

 

[brikis98]

Originally posted by: myocardia

Originally posted by: brikis98
i believe nvidia also stated the following:

Geforce 8800GTX SLI: 680W with 40A on the +12V rail (dual +12V rails and SLI certification recommended)

and if you know anything about these recommendations, they are always over-estimates to take into account low quality PSU's that buckle and have massive voltage drops when under heavy load. therefore, i state again: a high quality PSU w/ 40A on the +12V rail will work just fine for an 8800gtx sli setup.

Hmm, you have a horrible memory, I guess:

Originally posted by: brikis98
and i'd guess a high quality PSU with 30-35A on the +12v rail(s) will do the job as well.

wow, thanks for cutting out the rest of that sentence:

Originally posted by: brikis98
any reliable PSU with 40A total on the +12V rail(s) will be MORE than enough and i'd guess a high quality PSU with 30-35A on the +12v rail(s) will do the job as well.

so yes, i did restate what i said originally: 40A should be enough, assuming your PSU is of high quality and can actually provide 40A without a big voltage drop. as for the 30-35A part, i clearly said "i'd guess", which means i'm not sure and could very well be wrong. it would probably be pushing it and not advisable on a system with other high powered components (power hungry CPU, lots of HD's etc), but i'd GUESS that it might work if the system was fairly barebones.

to be fair, i don't have 8800gtx in sli, and i don't own any of those PSU's, so i can't state any of this with certainty and can only discuss based on what i've read.

 

[myocardia]

Originally posted by: brikis98

Originally posted by: brikis98
any reliable PSU with 40A total on the +12V rail(s) will be MORE than enough and i'd guess a high quality PSU with 30-35A on the +12v rail(s) will do the job as well.

so yes, i did restate what i said originally: 40A should be enough, assuming your PSU is of high quality and can actually provide 40A without a big voltage drop. as for the 30-35A part, i clearly said "i'd guess", which means i'm not sure and could very well be wrong. it would probably be pushing it and not advisable on a system with other high powered components (power hungry CPU, lots of HD's etc), but i'd GUESS that it might work if the system was fairly barebones.

to be fair, i don't have 8800gtx in sli, and i don't own any of those PSU's, so i can't state any of this with certainty and can only discuss based on what i've read.

You've done it again. The first time, you said that 40A should be more than enough, but you'd guess that 30A would be plenty, assuming it's a high quality psu. Now, you're saying, as long as it's a high quality psu, 40A should be enough. Explain to us how those two are comparable. The fact is, they aren't.

 

[JAG87]

so why are you even arguing with me.

first get the hardware and the talk. your arguments are based on theoretical numbers and recommended specs, while mine are based on real life experiences.

once again a power supply with 40A on the 12V rail will not run 8800 GTXs in SLI with stability. 20A is the minumum you should provide each card with and 40A in total should be used towards the VGA section. that leaves no power for the rest of the system. Hence 50A absolute minimum, 60A recommended.

otherwise enjoy your rebooting, BSODs, freezing, sound crackling, and so on. save those few bucks on the PSU after you spent 1.5k on videocards.

 

[Howard]

Christ, where are some of you people getting your figures from?

Fact: TDP of the 8800GTX is ~180W, meaning the worst case current draw will be 180/12 = 15A. In current systems, they're drawing more like 13A (but 15A is the number that should be allocated). Two of those and you get 30A draw for the video cards.

Processor - 5-11A (C2Ds are 5-7A)
Mobo - ~3A depending on the devices connected to it, how much memory, onboard sound/video, etc.
Video - 30A
HD - ~0.5A per
Optical drive - ~1A per
Misc. PCI cards - 0.5-1A per
Fans - 0.2-0.4A per (says on the hub sticker)

For a conventional rig with a C2D at ~3GHz, 2 HDs, 1 optical drive, 2 8800GTX cards, and two fans, that adds up to 42.6A. A PSU at 45A would be fine, although the cheapest one I'd recommend is the Corsair CMPSU-620HX with 50A. Perfect.

 

[brikis98]

Originally posted by: myocardia

Originally posted by: brikis98

Originally posted by: brikis98
any reliable PSU with 40A total on the +12V rail(s) will be MORE than enough and i'd guess a high quality PSU with 30-35A on the +12v rail(s) will do the job as well.

so yes, i did restate what i said originally: 40A should be enough, assuming your PSU is of high quality and can actually provide 40A without a big voltage drop. as for the 30-35A part, i clearly said "i'd guess", which means i'm not sure and could very well be wrong. it would probably be pushing it and not advisable on a system with other high powered components (power hungry CPU, lots of HD's etc), but i'd GUESS that it might work if the system was fairly barebones.

to be fair, i don't have 8800gtx in sli, and i don't own any of those PSU's, so i can't state any of this with certainty and can only discuss based on what i've read.

You've done it again. The first time, you said that 40A should be more than enough, but you'd guess that 30A would be plenty, assuming it's a high quality psu. Now, you're saying, as long as it's a high quality psu, 40A should be enough. Explain to us how those two are comparable. The fact is, they aren't.

give me a break - now you're just nitpicking at my grammar rather than actually providing any evidence to disprove what i said (whereas i at least tried to post some links backing up my reasoning).

STOP trying to twist my words and misquote me - it's rude, doesn't add anything to the discussion and doesn't help answer the original question. all i've been saying is that based on what i've read, 40A on the +12v rail(s) on a high quality PSU (as i've said EVERY time) should run the OP's system with 8800gtx's in SLI. i have little doubt of this statement, although as i've already said, i haven't actually tried it, so obviously i could be wrong. similarly, i would GUESS 30-35A would work as well, although i have more doubt in this scenario as it would be pushing it.

i did NOT say that "30A would be plenty", i said that i would GUESS that 30-35A will "do the job". i ALWAYS argued in favor of a high quality PSU, as the low quality PSU's don't work to spec, so that is irrelevant to the discussion. and yes, 40A SHOULD be enough because, as i've told you already, i can't state it FOR SURE as i haven't tried it myself.

again, stop arguing grammar and find some links that show that i'm wrong - if i am, i'll have no problem admitting it, but so far you've only been trying to play word games and you are NOT being helpful.