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Rough power consumption help?

King Damager

King Damager

King Damager

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I'm sure this has been asked somewhere but what are the required PSU W for crossfire or SLI?

Thinking about 6950/6970 crossfires and 560/70/80 SLI...

Thanks

kd
 
With the config in my sig (only the processor overclocked) here are some results I got with a monitoring socket measuring power draw from a wall socket to the PSU (PC display power draw not included).

Idle - 112.5 watts max
3dmark11 - 477.4 watts max
60 seconds of Kombuster - 524.8 watts max
About 15 minutes of Mafia 2 - 388.6 watts max
 
As the Anandtech link shows, its possible your system can draw upto 600W, assuming Furmark to be the max stress a PC will be under, now I know most peoples PCs will not be getting stresseed any where near this 99% of the time, but its possible that its draw could spike up to this level, no? And this was a non OCd system, so allowing for OCing and any extra devices/a little headroom, if it were me spending this much money on new PC hardware, Id be buying a quality 750W PSU to power it, rather than a 450/550W PSU to potentially have my system crash on me every time theres a spike in the power draw requirements as the PSU would not be able to provide what was required
 
Had a check on the Anandtech link for power use of dual 470's which im running, 740w with furmark, 579 for crysis. Thats for stock 607mhz cards, mine are 630mhz factory clocked versions, though i run them daily at 751 mhz on stock voltage, psu is a corsair hx 850w. I ordered a wall power monitor just after christmas, (still waiting on it). Would be interesting to see what the total system usage is with the cpu being oc'd.
 
1) Load in Furmark rises in time meaning that the system will draw more after an hour of stress-testing than a minute (as quoted by MichaelM).

2) The power calculators are mostly useless, they aren't much better than manufacturers' recommendations unfortunately. You can use them as a rough guide but the assumptions they make are inaccurate.

3) A system under Furmark is never fully stressed (it only stresses one CPU core). The most power draw you can force through your system will happen when Furmark and prime95 on all other instances are ran simultaneously.

4) An average system will not use anywhere near Furmark's load power.

5) Sudden peaks in current don't usually occur but they shouldn't affect the PSU nonetheless.

6) Core i7 920 @ 3.33GHz and 2xGTX 580s SLI in Crysis pull 620W from the socket. Make from that what you want but seing as the PSU tested can be as much as 90% efficient and knowing that Crysis is not the most stressful application that most users will run, make from that what you want. I'd advise 700W for a non-overclocked system and 850W if you plan on overclocking. Stay away from Furmark/Kombuster too.

7) Running prime95/IBT is fine for stress testing, Furmark is obsolete on the other hand. It's a useless piece of software that should be banned from use by unaware users.

8) I don't know how stressful Folding is. Someone who's into it should give us some info on it.
 
why do you people recommend more expensive psus when its clearly not needed? instead try to squeeze every bit of performance from your hardware the same way we do with overclocking.
 
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Its always nice to have a little extra juice on tap if you add other parts to your system, crossfire/sli being two prime examples.
 
Better safe than sorry.

With my system in that PSU calculator posted earlier it says 772W and that seems to be the power draw of components at 90% TDP (all together which is highly unlikely) added together and a 20% head room added to get a recommended minimum so with 772W on paper which means a 800W from a manufacturer. I think that calculator is a reliable source to find out what you need and maybe even takes into account sensible 24/7 GPU overclocking.

This is just my own opinion, I have not personally tested any of this:
I think with 80 Plus certified PSU's you also get atleast 80% efficiency at its rated draw and much nearer 100% the less stressed a power supply is, so if you have a 1000 watt PSU and your system is drawing 500 watts then like 96-98% of the power draw from the socket is used by the components while if your system is drawing 500 watts of a 500 watt PSU its really drawing 600 watts from the socket due to inefficiency of parts running max capacity.

With a good quality PSU its rated to draw its worst case with maximum efficiently while lower quality PSU's will burn out and maybe take components out as it goes.
 
NZXT30 said:
why do you people recommend more expensive psus when its clearly not needed? instead try to squeeze every bit of performance from your hardware the same way we do with overclocking.
Click to expand...

Because if someones building a PC for £1500 (for instance) is it really worth skimping and getting a 70 quid PSU as opposed to a hundred quid one and potentially running into problems? IMO no
 
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