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NewtonianRefractor
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Message 905691 - Posted: 10 Jun 2009, 4:54:00 UTC

This is an interesting article on xbitlabs about power consumption. http://www.xbitlabs.com/articles/coolers/display/system-wattage.html.

What do you guys think?
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Message 905752 - Posted: 10 Jun 2009, 12:19:53 UTC

Great info. Thanks for posting. My rule of thumb has always been to over size my power supplies. I know that none of my systems use anywhere near 100% of what is available. But it's also intersting to note how much varriation there is between types of sytems. Might have to start testing RAC per watt of various systems.
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Message 905842 - Posted: 10 Jun 2009, 17:14:22 UTC - in response to Message 905752.

Great info. Thanks for posting. My rule of thumb has always been to over size my power supplies. I know that none of my systems use anywhere near 100% of what is available. But it's also intersting to note how much varriation there is between types of sytems. Might have to start testing RAC per watt of various systems.

On power supplies, you absolutely need margin: if the power supply is running flat out, it won't be able to handle occasional spike, it will run a lot hotter, and it won't last long.

It's less important, but you have to be careful on the other end too. Most PC power supplies need some load, and if you use a 1000w power supply on a very low power Atom motherboard it may not be able provide accurate regulated voltages under 20 watts.
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Message 906250 - Posted: 11 Jun 2009, 17:50:59 UTC - in response to Message 905842.

Great info. Thanks for posting. My rule of thumb has always been to over size my power supplies. I know that none of my systems use anywhere near 100% of what is available. But it's also intersting to note how much varriation there is between types of sytems. Might have to start testing RAC per watt of various systems.

On power supplies, you absolutely need margin: if the power supply is running flat out, it won't be able to handle occasional spike, it will run a lot hotter, and it won't last long.

It's less important, but you have to be careful on the other end too. Most PC power supplies need some load, and if you use a 1000w power supply on a very low power Atom motherboard it may not be able provide accurate regulated voltages under 20 watts.


Very true Ned.

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Message 906476 - Posted: 12 Jun 2009, 6:19:55 UTC

Totally agree with you Ned. I have been using 550-600 watt power supplies for my Quads. Most do not have big GPU's. So I have about 50% headroom.

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Message 906515 - Posted: 12 Jun 2009, 8:21:26 UTC - in response to Message 905842.

Ned Ludd wrote:
...
Most PC power supplies need some load, and if you use a 1000w power supply on a very low power Atom motherboard it may not be able provide accurate regulated voltages under 20 watts.

Even if it does provide decent regulation, it will probably not be working efficiently. You might be wasting 20 watts in the PSU to provide 20 watts to the motherboard.
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Message 906754 - Posted: 12 Jun 2009, 16:56:35 UTC - in response to Message 906516.

Ned Ludd wrote:
...
Most PC power supplies need some load, and if you use a 1000w power supply on a very low power Atom motherboard it may not be able provide accurate regulated voltages under 20 watts.

Even if it does provide decent regulation, it will probably not be working efficiently. You might be wasting 20 watts in the PSU to provide 20 watts to the motherboard.
Joe

Well.....I think there would be very few who would set up a 1000w psu to run a 20w mobo......unless they were highly misinformed.......

It is said that you should "never ascribe to malice what is equally explained by stupidity."

... but it's probably not a case of being misinformed, but uninformed.

In my opinion, the power supply should not be more than 4 times the actual power draw, and not less than 1.2 times the actual draw.

My 16w server has a 60w power supply.
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Message 906769 - Posted: 12 Jun 2009, 17:21:43 UTC - in response to Message 906508.

Every one of my OC'd quads is on a 550W psu.......

Save the Frozen Nehi, which is employing a 750w Silencer.....

Mind you, the Kittyman is not doing any GPUing either...

And a mere 750w might do It for the lower end gpu cards, But not for the GTX295 and definitely not for two of them either. :D
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Message 907294 - Posted: 13 Jun 2009, 15:29:52 UTC

I may seem to have 'over-kill' on one of my PCs.....an 850W Modular PSU feeding an MSI P35 Platinum, Intel E6550 CPU (2.33GHz @ 1.066 GHz), 2 GB Patriot DDR2 RAM, 2 X NEC DVD 'burners', 2 X Hitachi 500 GB drives, an X-Fi Platinum and an elderly (but quite adequate) Radeon X1900XTX. Cost was a consideration, naturally, but, the biggest considerations were given to the current delivery capability and future upgrades. While there were PSU's that could meet the total demands of the system, when I looked more closely at things, it was not 'all light'. The amount of current that a PSU can safely deliver on the various 'rails', has to be considered - many modern multi-rail PSUs cannot match some of the older 'desireable' PSUs with their single rail, for current delivery.

I like peace and quiet, too....I will therefore, more likely, select a PSU with 12 cm fans running at, say, 1200 rpm, as against one with 9 cm fans running at 3000 rpm. Moving air, is noisy and I have gone down that path. With my choices and buying a quiet PSU that delivers the current needed on all the rails, I have also ended up with a PC, that is quieter, more powerful and cheaper to run, than a 3.2 GHz P4 that I used to run (and still have) with a 550w PSU.

Keep crunching, Iona XXX


PS. Did I mention that I have a CGLI Elect Tech Cert?
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Message 907379 - Posted: 13 Jun 2009, 21:36:55 UTC

For what it might be worth my i7 920 power consumtion is as follows:
250 watts idle
346 watts running 8 cores
335 watts running no cpu tasks with 1 gpu running Cuda
431 watts running no cpu tasks with 2 gpu's running Cuda
530 watts running full load 8 cores running cpu tasks and 2 gpu Cuda
I have a 850 watt active psu in the rig
Dave
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Message 907388 - Posted: 13 Jun 2009, 22:29:35 UTC - in response to Message 907339.

The amount of current that a PSU can safely deliver on the various 'rails', has to be considered - many modern multi-rail PSUs cannot match some of the older 'desireable' PSUs with their single rail, for current delivery.


Keep crunching, Iona XXX


PS. Did I mention that I have a CGLI Elect Tech Cert?

Single 12v rail power supplies are not a thing of the past.....
PC Power and Cooling still makes them, and they are some of the best PSUs I am aware of....I have a 750W Silencer on the Frozen Nehi, and it is efficient, cool, and quiet. Fine power supply.


Agreed. For all my high end builds I prefer to use PC Power and Cooling PSUs. In fact, I try to stay away from the multi-rail PSUs because its just too hard to track down a problem when you have too much loaded on a single rail that is under-powered. A single, powerful 12v rail works best.
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