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Recommended PSU wattage for this build...

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July 21, 2011 7:59:29 PM

These are the components I'm planning to get:

AMD Phenom II X6 1100T CPU /w CPU fan (@3.3 Ghz, no O.C. for now)
Asus Crosshair IV Formula Motherboard
4x 4GB, 2000Mhz, Dual Channel DDR3 RAM (about 1.6 Volts, also not O.C'ed)
3x Case Fans: One @1200 RPM, another @2000 RPM, and a thermally controlled fan that can go from 1500 to 2100 RPM
2x 2TB, 64 MB Cache, 7200 RPM Spindle speed HDDs (to be used in RAID 1)
2x AMD Radeon HD 6970 Graphics Cards (CrossfireX mode)
PCI Wireless N Network Card (300 Mhz)
DVD(+/-)RW Burner

I've checked the required wattage from a few different PSU calculators across the internet, and they all averaged around 1000 watts. I'm planning to use this computer for about 5 (or more) years, and I'm not going to O.C. these components for at least the first 2 years I have this. Therefore I'm thinking of getting a 1200W PSU to make up for the 5+ years of component aging. Will it work, or is the 1200 watts not needed for the long-run?
a c 274 ) Power supply
July 21, 2011 10:27:13 PM

What have you been putting into the PSU calculators, specifically in the capacitor aging field.

A good 850W unit would be more than enough for that system even with overclocking so im not sure why your PSU calculators are telling you 1kW but thats overkill. Capacitor aging unfairly inflates the eXtreme PSU calculators results, most units will never suffer more than 20% capacitor aging over 10 years, let alone their 10% for every year BS, and the newegg one inflates its results significantly.
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a c 87 ) Power supply
July 21, 2011 10:29:27 PM

Capacitor aging shouldn't be significant unless it is a bad PSU to begin with, or if the PSU is not ventilated properly/adequately. Basically +1 to hunter.

http://www.anandtech.com/show/4061/amds-radeon-hd-6970-...
http://www.legitreviews.com/article/1488/18/
These two reviews show ~600W being consumed at the wall when running furmark. The actual system power draw for them would be lower by 10-20% because of the efficiency of the PSU. So a worst case scenario for your maximum power consumption is going to be ~540W.

Based on this I would recommend a good 850W PSU, because a ~540W load would only stress such a PSU to ~63%.
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July 22, 2011 1:37:07 AM

850 watts? OK.

So does anyone know of an example of a 1200W computer build? And what is the downside of building a computer with a PSU with too much wattage (other than the waste of $$$ for something I won't need)?
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a c 274 ) Power supply
July 22, 2011 1:45:50 AM

If you wanted to do three high end cards, or two dual GPU cards, that would be a 1kW-1.2kW setup.

For the most part its just wasting money on something that you wont make full use of and likely never will make full use of, a good 850W unit is more than enough for 99.99% of systems out there, unless you are dropping 3k on a rig with multiple high end GPUs so the $300 PSU is only a small part of the budget its really just spending way too much for no reason. PSUs are also more efficient near about 50-75% load, so running a 1kW unit at 10% load when you are at idle will leave you sucking more power from the wall at idle than a similarly rated 850W unit would as it would be much closer to 20% load.
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July 23, 2011 1:14:42 AM

Quote:
If you wanted to do three high end cards, or two dual GPU cards, that would be a 1kW-1.2kW setup.



Dual GPUs? Do you mean the super-high end card like the Radeon HD 6990 (2x HD 6950s)?

Very nice suggestion though, thank you for the advice. :D 
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a c 274 ) Power supply
July 23, 2011 2:07:08 AM

Yeah, dual GPU cards are the 4870x2, 5970, 6990, GTX 295, and GTX 590, there are some older ones but the 6990 and GTX 590s are the most power hungry cards ever released, they pull more than 300W at full load at stock settings.
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