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PSU Wattage For 3 GPUs

N4g4rok

N4g4rok

Senior member
Putting together a rig that needs to run nine monitors, and i'm still unsure about how much wattage the PSU need to support for teh 3 GPUs going in it. It's a i5-2400 build with two 58530s and a 4860, and a couple PSU calculators seem to think that 750W will be enough. is that accurate?
 
http://www.geeks3d.com/20090618/graphics-cards-thermal-design-power-tdp-database/ reveals the TDP (thermal design power) limit of those graphics cards, i.e. the board's max designed power draw:

4850 TDP = 114W (x2), requires 1x 6-pin PCIe power connector from the PSU
5830 TDP = 175W x2 requires 2x 6-pin each

So in total you need a PSU that is capable of powering 464W worth of graphics cards via four five PCIe connectors.

650W units typically have only two connectors, while 750W units typically have four, so 750W is the minimum I'd recommend. edit: Need a molex->PCIe adaptor for that. 850W would be a good idea as well.

Since you're in the USA, I think this is the best bang for buck high quality unit: XFX 750W $95 $70 AR
 
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lehtv said:
http://www.geeks3d.com/20090618/graphics-cards-thermal-design-power-tdp-database/ reveals the TDP (thermal design power) limit of those graphics cards, i.e. the board's max designed power draw:

4850 TDP = 114W (x2), requires 1x 6-pin PCIe power connector from the PSU
5830 TDP = 175W, requires 2x 6-pin

So in total you need a PSU that is capable of powering 403W worth of graphics cards via four PCIe connectors.

650W units typically have only two connectors, while 750W units typically have four, so 750W is the minimum I'd recommend.

Since you're in the USA, I think this is the best bang for buck high quality unit: XFX 750W $95 $70 AR
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I could be wrong, but the way I read his post he is using 2 5830s and 1 4850, which would add on another 61W of power, plus another 6-pin connector.

OP could use an adapter for the last 6-pin though.
 
You're right, I misread that. It'd work on that 750W unit with one extra PCIe via adaptor, but with the extra 61W required it wouldn't be wrong to buy 850W.
 
I have a couple molex -> 6-pin adapters that originally came with the cards.

lehtv, when you say minimum that you'd recommend, is that implying that it might falter if all three cards start to experience a heavy workload, or it will work fine for full system load?
 
N4g4rok said:
Putting together a rig that needs to run nine monitors, and i'm still unsure about how much wattage the PSU need to support for teh 3 GPUs going in it. It's a i5-2400 build with two 58530s and a 4860, and a couple PSU calculators seem to think that 750W will be enough. is that accurate?
Click to expand...

what are you doing with the 9 monitors? sorry for being off topic
 
N4g4rok said:
lehtv, when you say minimum that you'd recommend, is that implying that it might falter if all three cards start to experience a heavy workload, or it will work fine for full system load?
Click to expand...

I wouldn't recommend anything that would have even a chance of faltering under full load. The XFX 750W unit is a good quality unit capable of delivering its full rated wattage continuously when needed. The +12V rail (which powers the GPUs and the CPU, mainly) is rated for 62A or 744W, while your components use less than 550W at full load with the CPU included. You'll never get close to its rated wattage.

Possible reasons to prefer 850W are lower PSU fan noise under load (edit: debatable though if that's a better approach than a higher efficiency 750W unit) and peace of mind in the long term if using the graphics cards doing power hungry computational work several hours a day. But if you just use the GPUs to run nine monitors instead of actually doing hard work, they will not be spending that much power.
 
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Nvidiaguy07 said:
what are you doing with the 9 monitors? sorry for being off topic
Click to expand...

Modular end tables that connect to form a grid. Basically, a 3 x 3 table of monitors. haha. The whole thing is also VESA mountable. The same set up was used for an openGL rubix cube demonstration a few years ago. The school it was done for gave the monitors back, now we don't know what else to do with them, other than make a table.
 
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lehtv said:
Possible reasons to prefer 850W are lower PSU fan noise under load and peace of mind in the long term if using the graphics cards doing power hungry computational work several hours a day. But if you just use the GPUs to run nine monitors instead of actually doing hard work, they will not be spending that much power.
Click to expand...

Excellent. I can't see the system doing anything more stressful than Minecraft, Netflix, and some adobe work. Thank you, sir.
 
N4g4rok said:
Modular end tables that connect to form a grid. Basically, a 3 x 3 table of monitors. haha. The whole thing is also VESA mountable. The same set up was used for an openGL rubix cube demonstration a few years ago. The school it was done for gave the monitors back, now we don't know what else to do with them, other than make a table.
Click to expand...
Neat project!

When you get it finished post some pics, or PM them to me.
 
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