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nVidia GTX295

T

The Borg

Senior member
Hi guys,

I am considering purchasing said graphics card for my main machine. It is an AMD X2 4800+ OC'ed slightly (2400 to 2735). It is probably underpowered for the card, but the reason for the nvidia card is so that I can run the GPU stuff - CUDA.

My board is an old PCIe 1.0. Will there be compatibility issues? I only have one 16 lane PCIe slot, so cannot go SLI or Crossfire.
Will it run full throttle crunching?
I have a 650W PSU. Would that be enough? I do have 8 HDD's in the box, but not much else.

Anything else I should be carefull about, or just can the idea until I get and i7?

Appreciate any comments.
 
I would think the mobo should work out - because there is not much data moving to and from the GPU. But I may be wrong - please check with the manufacturer if the GPU-card is compatible with PCIe v. 1.0!

The PSU sounds IMHO somewhat underpowered: The 295 pulls 219 W idle, and may pull 375 - 380W when fully engaged. The processor may pull 89 - 95W when fully engaged and then you have to calculate the Mobo (30 - 45W) the HDD (5 - 10 W), the HSF (10-15W) and maybe some more Watts ... that is already 520 - 530W. Your PSU - if it has 85% efficiency (which it probably does not have at that effect) gives 550W, if the efficiency is 80% then it yields 520W.

Look here for more info:

Power usage of GPUs.

A 650W PSU test - is your as efficient?

Some numbers about how much power components use.

 
Originally posted by: petrusbroder
The PSU sounds IMHO somewhat underpowered: The 295 pulls 219 W idle, and may pull 375 - 380W when fully engaged.
Click to expand...
A GTX295 has a theoretical maximum power draw of 300W, 75 from the PCIe slot, 75 from the 6pin connector and 150W from the 8pin connector. According to xbitlabs the actual power draw is ~215W. A decent 650W PSU should be more than capable.

Your PSU - if it has 85% efficiency (which it probably does not have at that effect) gives 550W, if the efficiency is 80% then it yields 520W.
Click to expand...
As PCTC2 mentioned, the efficiency works the other way around. It tells you how efficient the PSU is at converting the AC to DC. So a PSU with an 85% efficiency rating at 550W would require 647W from the wall (550/0.85 = 647).
 
I was thinking like this: the limit out of the wall is 650W. If you have an 80% efficiency then the internal parts can not draw more than 520W (650*0.8=520W) . if the efficiency is 85% then the load of the internal components can not be more than 550W (650W*0.85=552W). This does not contradict neither of you ... and it works both ways (520/0.8=650)


Your PSU - if it has 85% efficiency (which it probably does not have at that effect) gives 550W, if the efficiency is 80% then it yields 520W.
Click to expand...

So: the sum of the power used by all components can not be larger than 520W if your 650W PSU has an efficiency of 80%.

About the power draw of the GPU: according to the article the usage of the CPU and other components is very small.

All these results are taken at the wall (total system power) running the 3dmark Vantage POM (parallax occlusion mapping) shader test. This test uses very little other system resources and focuses on the GPU. This means that the numbers you see here are LOWER than total system power while playing a game -- often by more than 50W and sometimes 100W, depending on the game, benchmark and system. These numbers show clearer differences between GPU power draw, which is why we stick with them. These numbers should NOT be used to determine a proper PSU for a certain graphics card solution unless you consider a couple hundred watts of headroom in your calculation.
Click to expand...

I still think that the 650W PSU is slightly too small.


Edit: My above calculation is wrong, because the 650W of the PSU denotes the DC effect, not the AC-draw from the wall. My error ...
Thanks for the corrections above an below, theAnimal and mrSHEiK124!
 
Originally posted by: petrusbroder
I was thinking like this: the limit out of the wall is 650W. If you have an 80% efficiency then the internal parts can not draw more than 520W (650*0.8=520W) . if the efficiency is 85% then the load of the internal components can not be more than 550W (650W*0.85=552W). This does not contradict neither of you ... and it works both ways (520/0.8=650)


Your PSU - if it has 85% efficiency (which it probably does not have at that effect) gives 550W, if the efficiency is 80% then it yields 520W.
Click to expand...

So: the sum of the power used by all components can not be larger than 520W if your 650W PSU has an efficiency of 80%.
Click to expand...
No, a good quality 650W PSU will be able to provide all 650W if required. Assuming 80% efficiency then it would pull 812.5W from the wall. The 650W rating is DC, not AC.

About the power draw of the GPU: according to the article the usage of the CPU and other components is very small.

All these results are taken at the wall (total system power) running the 3dmark Vantage POM (parallax occlusion mapping) shader test. This test uses very little other system resources and focuses on the GPU. This means that the numbers you see here are LOWER than total system power while playing a game -- often by more than 50W and sometimes 100W, depending on the game, benchmark and system. These numbers show clearer differences between GPU power draw, which is why we stick with them. These numbers should NOT be used to determine a proper PSU for a certain graphics card solution unless you consider a couple hundred watts of headroom in your calculation.
Click to expand...

I still think that the 650W PSU is slightly too small.
Click to expand...
Anandtech shows a system with GTX295 and Core i7 only drawing 389 from the wall, and even with 85% efficiency that is only 331W internally. Add another 150W and it's still well within the capability of a good quality 650W PSU.
 
Originally posted by: theAnimal
Originally posted by: petrusbroder
I was thinking like this: the limit out of the wall is 650W. If you have an 80% efficiency then the internal parts can not draw more than 520W (650*0.8=520W) . if the efficiency is 85% then the load of the internal components can not be more than 550W (650W*0.85=552W). This does not contradict neither of you ... and it works both ways (520/0.8=650)


Your PSU - if it has 85% efficiency (which it probably does not have at that effect) gives 550W, if the efficiency is 80% then it yields 520W.
Click to expand...

So: the sum of the power used by all components can not be larger than 520W if your 650W PSU has an efficiency of 80%.
Click to expand...
No, a good quality 650W PSU will be able to provide all 650W if required. Assuming 80% efficiency then it would pull 812.5W from the wall. The 650W rating is DC, not AC.

About the power draw of the GPU: according to the article the usage of the CPU and other components is very small.

All these results are taken at the wall (total system power) running the 3dmark Vantage POM (parallax occlusion mapping) shader test. This test uses very little other system resources and focuses on the GPU. This means that the numbers you see here are LOWER than total system power while playing a game -- often by more than 50W and sometimes 100W, depending on the game, benchmark and system. These numbers show clearer differences between GPU power draw, which is why we stick with them. These numbers should NOT be used to determine a proper PSU for a certain graphics card solution unless you consider a couple hundred watts of headroom in your calculation.
Click to expand...

I still think that the 650W PSU is slightly too small.
Click to expand...
Anandtech shows a system with GTX295 and Core i7 only drawing 389 from the wall, and even with 85% efficiency that is only 331W internally. Add another 150W and it's still well within the capability of a good quality 650W PSU.
Click to expand...

This (to the calculation).

Efficiency refers to AC->DC conversion, NOT how much power you can use. A 650W power supply should have no problem giving you 650W at peak if you needed it (which he won't, not with that system). The proper calculation would be 650W/0.8 = 812.5W AC draw from the wall
 
Originally posted by: theAnimal

Edited by Petrusbroder:

Anandtech shows a system with GTX295 and Core i7 only drawing 389 from the wall, and even with 85% efficiency that is only 331W internally. Add another 150W and it's still well within the capability of a good quality 650W PSU.
Click to expand...

OK, I accept that. Thanks for the corrections above, theAnimal and mrSHEiK124!

I am still somewhat confused, but - I think - on a higher level ... 😉
 
Guys, as usual, you have managed to clear up an issue (with a bit of confusion along the way). Many thanks. I now feel happier about the possibility of popping in the 295 without exhausting a whole lot of smoke from the PSU.
 
There are things which can prevent a PSU from delivering its rated wattage. Age will reduce the output. If the PSU is rated at a lower temperature than that at which it operates, this will reduce output. And for modern systems the PSU needs to be able to provide a significant portion of its output on the 12V rails, otherwise the full capacity cannot be used.
 
I checked the specs of the PSU. It can produce 624W on the +12V rails. And 170W on the +3.3v and +5V. That what the box says!!!
 
Originally posted by: The Borg
I checked the specs of the PSU. It can produce 624W on the +12V rails. And 170W on the +3.3v and +5V. That what the box says!!!
Click to expand...

~52 amps on the 12V rail(s). That ain't too bad at all.
 
Yes, it is - strange - for a 650W PSU (Antec NeoPower 650 Blue). The 295 requires 46A or so - one of the website stats.
 
Originally posted by: The Borg
Yes, it is - strange - for a 650W PSU (Antec NeoPower 650 Blue). The 295 requires 46A or so - one of the website stats.
Click to expand...

The 650W NeoPower's are pretty solid PSUs, I wouldn't worry 🙂

I checked using a PSU calculator, 4800 X2 at 2735/1.4V, two DIMMs DDR, 8 HDDs, and 90% system load, it's giving me 573W. With any amount of age on the PSU, you lose a bit of output, if I were you, I'd upgrade to a Corsair or PC Power & Cooling 750W unit just to be safe. The GTX295 by itself does not use a lot of power; I've got a 620W Corsair unit with an overclocked C2Q, and I could very easily run a GTX295 in here. 8 HDDs add up though, I've only got two..
 
Originally posted by: mrSHEiK124
Originally posted by: The Borg
Yes, it is - strange - for a 650W PSU (Antec NeoPower 650 Blue). The 295 requires 46A or so - one of the website stats.
Click to expand...

The 650W NeoPower's are pretty solid PSUs, I wouldn't worry 🙂

I checked using a PSU calculator, 4800 X2 at 2735/1.4V, two DIMMs DDR, 8 HDDs, and 90% system load, it's giving me 573W. With any amount of age on the PSU, you lose a bit of output, if I were you, I'd upgrade to a Corsair or PC Power & Cooling 750W unit just to be safe. The GTX295 by itself does not use a lot of power; I've got a 620W Corsair unit with an overclocked C2Q, and I could very easily run a GTX295 in here. 8 HDDs add up though, I've only got two..
Click to expand...

The PSU calculator gives recommended PSU size, not power consumption.

If all 8 HDDs are busy at the same time, they'd use ~80-100W.
 
For what ever it's worth, my PCs are using 650W (Antec) PSUs. They are overclocked Q6600 and two reasonably beefy video cards (8800GTS & 9800GTX+)

This warms up the PSU to be sure, but I have seen no indication that I am pushing them too hard.

-Sid
 
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