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PSU that can handle two gtx 280's

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June 2, 2008 1:57:02 AM

I have a Thermaltake Toughpower 850w PSU. I am going to get a GTX 280 (which has a TDP of 236 watts) when it comes out along with all the supporting components. If i were to get a second GTX 280 down the road, would the 850w PSU be able to handle it? I will only use one HDD, core 2 q9450, 4 or 8 gigs of ddr2, all on a evga 750/780/790i mobo. Thanks

More about : psu handle gtx 280

June 2, 2008 2:18:48 AM

Nope, low quality PSU and low wattage. Get a 1kw PSU for safe measures.

List of good ones from best to least good:
-Enermax Galaxy S DXX 1000w (best)
-PC Power and Cooling Turbo-cool 1000w
-Corsair 1000hx
-Silverstone ST1000
June 2, 2008 2:52:15 AM

Impossible to know until we see some definitive reviews.
Related resources
June 2, 2008 2:57:40 AM

toughpower is not a low quality psu by any stretch of the imagination... 850w will be cutting it close though, especially if you oc. you'd need close to 500w for the video cards with an oc and a heavy load, and at least another 200w for the rest of the components, you want to run a psu at around 50-60% load for best efficiency and less strain on the psu. 1kw would be your minimum.
June 2, 2008 3:16:55 AM

Don't listen to Blood Raven.. the Toughpower PS's are great quality, and 850w will most likely be plenty with just your other components.

A normal system (no o.c. and weak/no video card) can get by on 200w of power. Raise to 300 for a good system, and 250*2 for the video cards.. and you come out with 800 total watts.. And im being fairly liberal with those figures.. You'll be fine with what you have
a b ) Power supply
June 2, 2008 3:26:20 AM

A PCI-E 2.0 card can get 300W at most, assuming it has a 6-pin and an 8-pin connector. At worst, your two cards will get 600W. With a quad CPU and the MB and the HDD, it's awfully close to the 850W limit. I think your PSU will do the job, but it will be very close to max. That will lower its efficiency and lifetime and it will increase the noise and heat.

I suggest you buy one card for now, and then do more research. Buy a new PSU together with the second card, if a new PSU is really needed. It's really hard to tell now. For example those cards may consume only 200W, not 300W, we don't know yet.

a b ) Power supply
June 2, 2008 3:34:17 AM

OK, I got a few more numbers for you. The GTX 280 will have 240 stream processors, and will use the same technology as the 9800GX2 (which has 128*2). This means the power requirements of the GTX 280 should be similar to those of the 9800GX2, maybe a bit lower - it depends on clocks.

PSUs certified for two 9800GX2 cards include the Toughpower 1000W but not the 850W.
The list is here.
http://www.slizone.com/object/slizone_build_psu.html

June 2, 2008 6:10:42 AM

The_Blood_Raven said:
Nope, low quality PSU and low wattage. Get a 1kw PSU for safe measures.

List of good ones from best to least good:
-Enermax Galaxy S DXX 1000w (best)
-PC Power and Cooling Turbo-cool 1000w
-Corsair 1000hx
-Silverstone ST1000



I hate to reenerate others, but aren't most thermaltake PSU's on the "80 plus" list?

I have a thermaltake toughpower cable management myself and every single thermaltake review i've read pointed to them being excellent PSUs
June 2, 2008 6:47:35 AM

That's because stupid people listen to power supply marketing. As far as running your power supply at a high load, why not, you paid for that capacity, use it up.
June 2, 2008 6:50:46 AM

why use two of these cards to run high AA at a millionxkagillion resolution at 60fps.
June 2, 2008 7:27:30 AM

by the way things are sounding about the new Gtx 2x0's it look like they going to be fricken awesome, and i think it would be a little overkill to buy two of those giants....unless you just need to waste more of your endless supply of money on something......you know...whatever tho...just my 2 cents...
June 2, 2008 8:07:35 AM

jeffisc001 said:
I have a Thermaltake Toughpower 850w PSU. I am going to get a GTX 280 (which has a TDP of 236 watts) when it comes out along with all the supporting components. If i were to get a second GTX 280 down the road, would the 850w PSU be able to handle it? I will only use one HDD, core 2 q9450, 4 or 8 gigs of ddr2, all on a evga 750/780/790i mobo. Thanks


your PSU should be able to hold up with that load, but since you have the $$$ for 2 x GTX 280's then you shouldnt have issues any way - wait for reviews and see.

PS. if an AcBell 400 can handle a high end system with a 8800GTS (640mb) then im sure yours will handle the 280's ;) 
June 2, 2008 10:48:57 AM

80 certified doesn't mean its a good PSU, just means it pulls less power from the wall, and so helps with the electric bill. Thermaltake power supplies in general are not the greatest, and the 850w has been known to have stability issues even more pressing than the rest of the toughpower series. Do some research, do not tell me I'm wrong because you bought a Thermaltake power supply, I hate that. The Thermaltake power supplies usually get the job down, however, but the problem is that his system would run damn close to 750-800w which is dangerous to even a great PSU. aevm is absolutely right though, those figures could change drastically soon but by the information you presented, then no that PSU will not work, sorry.
June 2, 2008 11:22:11 AM

It might, there are power supplyies that can deliver over 100 percent load, not many though, and I would not want to. Plus if you oc your gonna draw a LOT of power, lots more than stock by at least half again I bet...it all depends on a lot of variables and we better wait for the reviews or it's just guessing.
June 2, 2008 4:22:22 PM

I would venture to say a PP&C 860 watt will do the job. A 1Kw powersupply is really a waste in all but the most demanding systems. If you run a 1Kw but only use 700ish watts, your actually wasting alot of money just on your electric bill.
a b ) Power supply
June 2, 2008 4:34:18 PM

Kaldor said:
I would venture to say a PP&C 860 watt will do the job. A 1Kw powersupply is really a waste in all but the most demanding systems. If you run a 1Kw but only use 700ish watts, your actually wasting alot of money just on your electric bill.


The PC P&C is actually certified for two 9800GX2 cards, which in fact contain more stream processors than two GTX 280s, so yeah, I believe you're right there.

Your other statement though is completely wrong. A system that needs 700W and runs on a 700W PSU will cost you MORE than the same system running on a 1000W PSU, all things being equal. For example a 700W PSU that normally reaches 85% efficiency at its best will work at less than 80%, maybe as low as 70%, when pushed close to 700W. A 1000W that normally reaches 85% efficiency at its best will work at about 85% when pushed to 700W. With the 700W PSU you consume 700W*100/70 = 1000W from the wall (assuming 70% efficiency at the end of the supported range), while with the 1000W PSU you consume 700W*100/85=823W . That is, the 1000W PSU SAVES you 177W on your bill, while the 700W PSU makes you pay for it, and even worse, it turns it into heat inside your case.

Look, the power rating of a PSU is not the amount it uses from the wall. It is the MAXIMUM amount that it should be allowed to draw. Ideally you should aim for a PSU that is used at 50% to 75% of its maximum, to get the maximum efficiency of the PSU and minimize bills and heat. How much your system needs depends on GPU and CPU and disks, not on the PSU size.

June 2, 2008 4:41:51 PM

It should handle the cards more than fine.
Even when OC'd the Q9450 does not draw too much power.
June 2, 2008 4:48:05 PM

aevm said:
The PC P&C is actually certified for two 9800GX2 cards, which in fact contain more stream processors than two GTX 280s, so yeah, I believe you're right there.

Your other statement though is completely wrong. A system that needs 700W and runs on a 700W PSU will cost you MORE than the same system running on a 1000W PSU, all things being equal. For example a 700W PSU that normally reaches 85% efficiency at its best will work at less than 80%, maybe as low as 70%, when pushed close to 700W. A 1000W that normally reaches 85% efficiency at its best will work at about 85% when pushed to 700W. With the 700W PSU you consume 700W*100/70 = 1000W from the wall (assuming 70% efficiency at the end of the supported range), while with the 1000W PSU you consume 700W*100/85=823W . That is, the 1000W PSU SAVES you 177W on your bill, while the 700W PSU makes you pay for it, and even worse, it turns it into heat inside your case.


Most PSUs dont hit their efficiency peak until 80% load. If you have a 1Kw PSU and only use 700 watts, your PSU is probably running inefficiently. However, an 850 to 900 watt PSU using 700 watts is probably right where it needs to efficiency wise. There are exceptions to this rule, as all PSUs are not equal. I would never suggest running a PSU at max load for any length of time, other than maybe to test it in a lab. A cushion of 25% of watts needed is more than enough and is what I recommend, IE if a system needed 600 watts to operate, I recommend a 750 watt PSU, as anything more does nothing.

Heat inside the case is a non factor unless you have a power supply that pumps hot air inside the case instead of exhausting it.
June 2, 2008 4:51:34 PM

700-800 W should do the trick.
a b ) Power supply
June 2, 2008 5:04:23 PM

Kaldor said:
Most PSUs dont hit their efficiency peak until 80% load. If you have a 1Kw PSU and only use 700 watts, your PSU is probably running inefficiently. However, an 850 to 900 watt PSU using 700 watts is probably right where it needs to efficiency wise. There are exceptions to this rule, as all PSUs are not equal. I would never suggest running a PSU at max load for any length of time, other than maybe to test it in a lab. A cushion of 25% of watts needed is more than enough and is what I recommend, IE if a system needed 600 watts to operate, I recommend a 750 watt PSU, as anything more does nothing.

Heat inside the case is a non factor unless you have a power supply that pumps hot air inside the case instead of exhausting it.


The peak seems to be around 50% for these OCZ models for example. I've seen charts like that where the peak comes later. Anyway, it's never near 100% AFAIK.
http://www.anandtech.com/casecoolingpsus/showdoc.aspx?i=3280&p=8

Yes, I agree about the heat thing, it depends on how the PSU works. That's why I prefer PSUs that pump the air out the back (like the Silencer 750W) rather than vertically (say, Toughpower 850W). The vertical ones don't make sense to me - the air goes up to the CPU and GPU, or down into the floor and then it comes back :( 
June 2, 2008 5:10:12 PM

Kaldor said:
Most PSUs dont hit their efficiency peak until 80% load.

I'm not sure where you got your information, but I believe it's wrong. Examples:

Zalman 1KW - 40% load @ max efficiency
http://www.silentpcreview.com/article834-page4.html

Corsair 650TX - 46%
http://www.silentpcreview.com/article813-page4.html

Enermax Modu82+ 625W - 40%
http://www.silentpcreview.com/article813-page4.html

From everything I've heard and read, the max efficiency is ~40-55%. Don't post information without proof.

I second the Toughpower is a very good PSU. Most TTs suck, but the Toughpower line is the exception (similar to the Tier 2 XClio GreatPower line). I also would not suggest your PSU will or will not handle the SLI GTX280s, since no one has (publicly) reviewed them yet.
June 2, 2008 5:28:10 PM

aevm said:

Yes, I agree about the heat thing, it depends on how the PSU works. That's why I prefer PSUs that pump the air out the back (like the Silencer 750W) rather than vertically (say, Toughpower 850W). The vertical ones don't make sense to me - the air goes up to the CPU and GPU, or down into the floor and then it comes back :( 


Yup. Ive taken PSU's apart and turned the fan around to get it to pull or push air out rather than pumping it in. Also has been a few times where Ive put a different fan in.

KyleSTL said:
I'm not sure where you got your information, but I believe it's wrong. Examples:

Zalman 1KW - 40% load @ max efficiency
http://www.silentpcreview.com/article834-page4.html

Corsair 650TX - 46%
http://www.silentpcreview.com/article813-page4.html

Enermax Modu82+ 625W - 40%
http://www.silentpcreview.com/article813-page4.html

From everything I've heard and read, the max efficiency is ~40-55%. Don't post information without proof.


Yep, stupid me. For some reason I got stuck on that 80+ thing, heh. At times my brain cramps and I type something without thinking about it fully. Anandtechs PSU reviews really do a nice job of showing where your going to hit you most efficient point with the PSU.

Edit: I think what I was trying to say is that efficiency peaks around 80% load. Anything more and most start to lose it. Its Monday, and Im losing it allready.......
June 2, 2008 6:02:24 PM

The_Blood_Raven said:
80 certified doesn't mean its a good PSU, just means it pulls less power from the wall, and so helps with the electric bill. Thermaltake power supplies in general are not the greatest, and the 850w has been known to have stability issues even more pressing than the rest of the toughpower series. Do some research, do not tell me I'm wrong because you bought a Thermaltake power supply, I hate that. The Thermaltake power supplies usually get the job down, however, but the problem is that his system would run damn close to 750-800w which is dangerous to even a great PSU. aevm is absolutely right though, those figures could change drastically soon but by the information you presented, then no that PSU will not work, sorry.


When making senseless arguments such as the quote one above, please use sources to back up your "facts" and not simply tell others to "just search for it"

I would recommend at least a good-quality 800W, the more the better I figure. Factor in future upgrades or if you can pass this PSU on to your next system.

Thermaltake is a fine brand.
June 2, 2008 6:25:14 PM

Kaldor said:
For some reason I got stuck on that 80+ thing, heh.
So then you agree that this statement is total BS.
Kaldor said:
If you run a 1Kw but only use 700ish watts, your actually wasting alot of money just on your electric bill.




And this statement is correct.
aevm said:
Your other statement though is completely wrong. A system that needs 700W and runs on a 700W PSU will cost you MORE than the same system running on a 1000W PSU, all things being equal. For example a 700W PSU that normally reaches 85% efficiency at its best will work at less than 80%, maybe as low as 70%, when pushed close to 700W. A 1000W that normally reaches 85% efficiency at its best will work at about 85% when pushed to 700W. With the 700W PSU you consume 700W*100/70 = 1000W from the wall (assuming 70% efficiency at the end of the supported range), while with the 1000W PSU you consume 700W*100/85=823W . That is, the 1000W PSU SAVES you 177W on your bill, while the 700W PSU makes you pay for it, and even worse, it turns it into heat inside your case.

Look, the power rating of a PSU is not the amount it uses from the wall. It is the MAXIMUM amount that it should be allowed to draw. Ideally you should aim for a PSU that is used at 50% to 75% of its maximum, to get the maximum efficiency of the PSU and minimize bills and heat. How much your system needs depends on GPU and CPU and disks, not on the PSU size.
June 2, 2008 6:51:00 PM

PC Power & Cooling units are -constant load- rated...not surge like other companies.
Anonymous
a b ) Power supply
June 2, 2008 6:52:30 PM

lolol... the psu wattage tracker thing... I just made a system that requires 16000 watts... or 16 1000 w psus...

lol
June 2, 2008 6:57:31 PM

Meh, I mispoke when I wrote that and didnt go back and edit. It should read "If you run a 1Kw but only use 700ish watts, your actually wasting alot of money." The point Im making is most people go and buy a 1Kw PSU when they only need an 850 watt. More power must make it better right?

I dont quite get what you pointing at with aevm's quote?
June 2, 2008 7:27:59 PM

Still missing the point, Thermaltake power supplies get the job done as I have said, but they are not the highest quality. You have an average (MAYBE slightly above average) PSU being pushed that close to its peak output, then yes you have problems. Also the PC P&C 860w is not as stable as the 610/750w versions. Just get a 1000w PSU that will be plenty anything below that will be pushing it and with OC then you are DEFINATELY in the red zone. I also say the Enermax Galaxy S DXX is best because it is rated about the same in stability and heat control as the PC P&C Turbo-Cool, though the PC P&C is slightly better. Where the Enermax Galaxy S DXX shines is in it's partially modular design and reasonable price compared to the Turbo-Cool which is half again as much.
a b ) Power supply
June 2, 2008 7:36:29 PM

I got to agree with that. That Enermax Galaxy is a fantastic PSU, and some book authors actually consider it #1.

But, the OP already has a pretty good (and rather expensive) PSU. If that can do the job, he should keep it IMO. We'll know if it can do the job once the video cards are out and measured.

I wonder, why would anybody need two GTX 280 cards? That's like 4 times the raw power of my trusty 8800GTX, for crying out loud...
June 2, 2008 11:45:46 PM

Kaldor said:
Meh, I mispoke when I wrote that and didnt go back and edit. It should read "If you run a 1Kw but only use 700ish watts, your actually wasting alot of money." The point Im making is most people go and buy a 1Kw PSU when they only need an 850 watt. More power must make it better right?

I don't quite get what you pointing at with aevm's quote?
I posted that because it is a common misconception that a larger power supply uses more power, which is exactly what you said. If what you are saying now is that you would be spending additional cash on wattage capacity that would not be used then that's fine, depending on the total draw of the machine after all of the facts of the GTX 280 come out.

I just wanted to be sure that everyone knew that a 1kW PSU and a 600W PSU will both deliver X watts of power at the same cost, assuming that they have the same efficiency at that wattage.

I wasn't expecting you to go back and edit your post, it would have actually made the thread more confusing, my post was to clarify for other people that don't understand PSUs at all, and might stumble on this thread and get the wrong idea.
June 3, 2008 8:40:52 AM

Kaldor said:
Yup. Ive taken PSU's apart and turned the fan around to get it to pull or push air out rather than pumping it in. Also has been a few times where Ive put a different fan in.



Yep, stupid me. For some reason I got stuck on that 80+ thing, heh. At times my brain cramps and I type something without thinking about it fully. Anandtechs PSU reviews really do a nice job of showing where your going to hit you most efficient point with the PSU.

Edit: I think what I was trying to say is that efficiency peaks around 80% load. Anything more and most start to lose it. Its Monday, and Im losing it allready.......


uhhhhhhhh as in reverse so that hot PSU air goes back into the case? wtf

psu fans take air from the case and pump it out the back as there supposed to, if the fan is in that config at that power output, thats what its designed for and tested with - leave them be, also voids the warranty etc.

June 3, 2008 3:20:20 PM

Kaldor wrote :

Yup. Ive taken PSU's apart and turned the fan around to get it to pull or push air out rather than pumping it in. Also has been a few times where Ive put a different fan in.


apache_lives said:
uhhhhhhhh as in reverse so that hot PSU air goes back into the case? wtf

psu fans take air from the case and pump it out the back as there supposed to, if the fan is in that config at that power output, thats what its designed for and tested with - leave them be, also voids the warranty etc.


Read this closer. "pull or push air out" is the key here. Ive seen more than a few PSUs that push hot into the case, but manufacturers are smarter now than they were 3-4 years ago, and I see less PSUs pumping air into the case. Chances are if you have one blowing air in, its a cheapy anyway. The objective is to get the hot air out. Thats why you would turn a fan around.

I really dont worry about a warranty on a old PSU in and old PC that I may be working on. Even if it was new, and the manufacturer was stupid enough to put the fan in backwards, if the fan was blowing into the case, Id tear it down and flip the fan. A warranty on a cheap PSU doesnt mean squat anyway. Whoa, a warranty on a $60 PSU, awesome. Think Tommy Boy and the box line he used to sell brakes.
June 3, 2008 6:14:15 PM

Kaldor said:
Ive seen more than a few PSUs that push hot into the case, but manufacturers are smarter now than they were 3-4 years ago,

I'll take your word on that one, because I have no proof they did/did not exist in the past.
Kaldor said:
and I see less PSUs pumping air into the case.

Like zero?!?!? I've never seen one before. I'm siding with apache on this one.
June 3, 2008 7:24:10 PM

I've seen em, cheap OEM PSUs or all of the old dell PSUs, it's terrible.
June 3, 2008 8:02:34 PM

apparantly GTX280 can do Tri-SLI lol are you ready for it!!!!!
June 3, 2008 10:23:16 PM

The_Blood_Raven said:
I've seen em, cheap OEM PSUs or all of the old dell PSUs, it's terrible.

OK, I can buy that, but in this thread we're talking about RETAIL, and that completely negates the original comment about fans. And I agree, that kind of design is terrible.
June 4, 2008 8:37:43 AM

The_Blood_Raven said:
I've seen em, cheap OEM PSUs or all of the old dell PSUs, it's terrible.


Very rare to see em these days, the bad old days (p1's, early P2's etc) maybe, but like in the last year seen none and i work retail/repair centre.
January 4, 2009 9:56:17 PM

can you help me on what psu i would need or you recommended for this system

2x gtx 280's
6gb corsair cl9 ddr3 1600 memory
lg bluray rom
146 seagate cheetah sas 15k rpm
500gb seagate 7200 rpm
asus p6t deluxe x58 motherboard
intel i7 920 cpu
5.25" memory card reader
noctua cpu cooler

im thinking i need at least 1000w but been looking at the cool master real power pro 1200w, what you think?

January 5, 2009 8:57:40 AM

4157longb said:
can you help me on what psu i would need or you recommended for this system

2x gtx 280's
6gb corsair cl9 ddr3 1600 memory
lg bluray rom
146 seagate cheetah sas 15k rpm
500gb seagate 7200 rpm
asus p6t deluxe x58 motherboard
intel i7 920 cpu
5.25" memory card reader
noctua cpu cooler

im thinking i need at least 1000w but been looking at the cool master real power pro 1200w, what you think?


Perhaps a good 850w? Check with the PSU calculators (google it).
!