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What PS?

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Originally posted by: 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.
Click to expand...
Howard, the reason we're arguing is because a)your numbers look about right, but forget to factor in the known 10-20% per year power loss of psu's, and b)42.6A continuous can't be put out by a psu with a 40A continuous output. Some people just don't like admitting when they're wrong, even when it's quite obvious that they are.
 
Originally posted by: 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.
Click to expand...

* aside from nvidia's quoted numbers, i also posted links from hardware review sites (including anandtech) that are showing REAL WORLD performance of these GPU's
* what exactly is your experience? have you tried a high quality PSU with 40A on the +12V rail and found it not enough (and made sure it wasn't just a faulty PSU)? have you measured the actual power draw of two 8800gtx's? if so, why don't you explain how and post the exact numbers to be helpful?
* if you notice the PSU's i originally recommended, all have more than 40A on the +12V rail (although only one has 60A). while i've argued that 40A should be enough, my recommendations reflect that i'm NOT saying to avoid getting anything with more than that, as having more headroom is better than less.
 
you need 50A minumum and 60A recommended for C2D + 8800 GTX SLI

take it from the guy who actually owns the hardware
 
Originally posted by: myocardia
Originally posted by: 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.
Click to expand...
Howard, the reason we're arguing is because a)your numbers look about right, but forget to factor in the known 10-20% per year power loss of psu's, and b)42.6A continuous can't be put out by a psu with a 40A continuous output. Some people just don't like admitting when they're wrong, even when it's quite obvious that they are.
Click to expand...

have any link to this PSU power loss issue you bring up? i've never heard of it and that seems awfully high. take for example your PSU with 60A on the +12V rail... if it loses 10% per year (as seems to be your minimum power loss), then it would be down to about 44A after 3 years, which according to you means the OP's machine would suddenly not work any more... seems unlikely to me, esp. with a high quality PSU, but if you have proof, please link it.

and i have no problems admitting i'm wrong, but other than speculation, you haven't provided one shred of evidence to prove me wrong. i will gladly admit i'm wrong if you can explain what's wrong with this reasoning:

according to anandtech, the MOST a single 8800gtx system (that's the WHOLE computer) uses under load is 301W. I did this analysis before: if we make the VERY CONSERVATIVE assumption that this is entirely from the GPU and is all over the +12V rail, that's 301W/12V = 25A. Using Howard's (conservative) estimate of 15A for an additional 8800GTX, that's a total of 40A.

So, with VERY conservative numbers, i get that a system with 8800GTX's in SLI will draw at the absolute most 40A, which means you'd want a 45A PSU to be on the safe side. realistically though, the system would use much less and you should (oh noes! i used the word should!) be fine with 40A or i would even GUESS (ah? what's that scary word mean?) 30-35A.

EDIT: again forgot to mention that these are minimums and if you look at the actual PSU's i recommended much earlier in the thread, i'm not actually advocating getting the bare minimum, but simply saying 60A is a gross overestimate.
 
Originally posted by: JAG87
you need 50A minumum and 60A recommended for C2D + 8800 GTX SLI

take it from the guy who actually owns the hardware
Click to expand...

saying that is useless unless you've actually measured the power draw to conclude that it's anywhere close to 50A.
 
in any case my word is worth more than yours in this situation because

#1 i have the hardware
and #2 i actually get to test many parts and run into just as many problems as well
 
Originally posted by: myocardia
Originally posted by: 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.
Click to expand...
b)42.6A continuous can't be put out by a psu with a 40A continuous output.
Click to expand...
That depends on how you define continuous output. A lot of PSUs can output more than they're rated for. Take for example this Zippy supply rated at 45A:

http://www.overclockers.com/articles1313/index02.asp
 
Originally posted by: JAG87
in any case my word is worth more than yours in this situation because

#1 i have the hardware
and #2 i actually get to test many parts and run into just as many problems as well
Click to expand...
How did you figure out 49A wasn't good enough?
 
Oh sure...I go ta bed...get up...read the thread and now i'm TOTALLY lost! So...after all this talk.......what is a nice safe way to go, that won't cost me an arm and a leg (at or under 400$ maybe?)

?????
 
Originally posted by: KyleGates
Oh sure...I go ta bed...get up...read the thread and now i'm TOTALLY lost! So...after all this talk.......what is a nice safe way to go, that won't cost me an arm and a leg (at or under 400$ maybe?)

?????
Click to expand...

under 400 ?
wow if your willing to go that far with your budget make no mistakes!!

Enermax Galaxy 850W
Enermax Galaxy 1000W
Silverstone Olympia 1000W

I particularly reccommend the Silverstone if you can find it instock anywhere. It is the only power supply equipped with four pci-e 6 pin connectors, and two pci-e 8 pin connectors (which might come in handy when R600 comes out. wink wink.)

*edit*
the olympia also has ONE 80A 12v rail, making it the most powerful single rail PSU on the market. The galaxy 850W has four 17A rails, and the 1000W has five 17A rails.
the only place I could find the Olympia is here and for 280.00 its steal. It will be instock Friday Dec 8. So order it now. You will be a happy camper and will never need another PSU again.
 
Originally posted by: JAG87
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.
Click to expand...

"Theoretical numbers"??? What the hell are you talking about?

Read THIS very carefully. Quad core Intel CPU, 8800GTX, 650i motherboard, Raptor HD; 320 watts, thats what Dailytech measured from the wall with a kilowatt meter. Thats how much the system drew under full load, there isn't anything theoretical about it.

For the sake of generous estimate assume that 100% of the power is 12v and don't factor in the AC to DC conversion and you still only have 27 amps (I rounded up) for the entire system.
 
Originally posted by: JAG87
Originally posted by: Beachboy
Get this. Link

It will definitely handle your requirements and it's well below $400. :thumbsup:
Click to expand...


single 60A 12V+ rail

:thumbsup:
Click to expand...

Jees. There's no way that's going in any of my systems.

I'm certainly not going to be installing an arc welder in my PC.

The recommendation for 20A max per rail is there for a reason - 60A will cut through metal and start fires without tripping any overload circuits.
 
The 8800GTX power draw misinformation in this thread is staggering.

From HardOCP

To put it into estimates, a GeForce 8800 GTX with its specified total thermal displacement of 185 watts, is going to add a solid 150 watts of load to your PSU when you put it into your system. The GeForce 8800 GTS is looking to come in well below that at around 110 watts of real world consumption.

From Anandtech
Total system power consumption when running our benchmarks, at times, peaked at over 520W with the SLI setup.

From VR-Zone
How about power consumption? Running the 3D Mark 06 HDR1 Test at 1600x1200 16xAF pretty much applies one of the heaviest load on a GPU. The 8800GTX consumes about 23 watts more than the 7950GX2 and 11 watts more than the X1950XTX. Really not that bad when you look at the performance it offers, or actually, it's performance per watt ratio is great.

From PC Perspective
292Watts for a system with an X6800 and a 8800GTX, running 3DMark06 at 2560x1600.


From all the reviews I've read, 8800GTX power draw hovers around 180W - that's 15A.

2 8800GTX -> 360W -> 30A
1 QX6700 -> 130W -> 11A

So where's the need for a 60A MINIMUM for 8800GTX SLI? Sure you might want one just to feel more secure but that's just an opinion, not fact. nVidia doesn't help this much themselves when they recommend a 450W PSU for a single-card setup and 850W PSU for dual-card setup. The second card doesn't add 400W but I guess it helps the guys in the SLI-Certification program sell more higher-end parts.

Scare-mongers spreading (mis)information like this is the reason Ultra came out with a 2000W PSU. 'OMG, there's a 2KW PSU out. That must mean I must have a minimum 1KW PSU just to be safe'.

I can't believe brikis98 is being flamed for talking sense - especially by the guy who believes a PSU with 60A on the 12V rail can't handle a Core 2 Quad and 8800GTX SLI.
:disgust:
 
Originally posted by: Gouv
Yes. Jag87 is probably a power supply vendor. Sure looks like (and acts) like a clown.
Click to expand...

you come into the thread 2 month later, contribute absolutely nothing and mock me.

permaban.
 
I told him that his PSU is adequate for running his setup. It might save him $200; that contributes something.

It's not my fault that your icon is a clown, and you didn't read the reviews.
 
Originally posted by: JAG87
you need 50A minumum and 60A recommended for C2D + 8800 GTX SLI

take it from the guy who actually owns the hardware
Click to expand...

Your word means nothing. Have you ever tried to power that system on less than 50A? No? Oh well then you really have no idea what kind of power requirement you really need - you just went with overkill. If you had tried and failed then you might know something but it really seems like you don't.

Originally posted by: Operandi

Read THIS very carefully. Quad core Intel CPU, 8800GTX, 650i motherboard, Raptor HD; 320 watts, thats what Dailytech measured from the wall with a kilowatt meter. Thats how much the system drew under full load, there isn't anything theoretical about it.
Click to expand...

Just to expand on that a bit:
Power consumption was measured using a Kill-A-Watt power meter that measures a power supply?s power draw directly from the wall outlet.

320w from the wall is not 320w from the PSU. The Toughpower listed claims 85% efficiency, and at around that load it's closer to 83% but we'll use the better number.

320w from the wall means the power supply is delivering 272w total output for an entire system. If that was all from the 12V it would be 23A for the entire system but of course it is not all from the 12V. Lets be generous and say 20A load. You can't tell me a GTX requires 20A EACH when faced with these numbers.
 
QX6700 = 130w TDP
8800 GTX = 185w TDP (x2)
gross power with no overclock = 500w (just cpu + the 2 cards)

your computer with 500w power supply constantly rebooting = priceless


 
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