I measured the wattage my tower uses from the wall.

[[Jett-R]-Giant]

This thread is to hopefully clear up some misconceptions about how big of a psu you really need. People seem to think they NEED a 800-1000W psu. I have yet to see the system that need that much power. And the latest PSu calculators tell me I MUST buy a 700W+ psu. To that I say PHHT!

My system is as follows:
GA-965P-DS3 rev3.3
E4300 @ 3.0GHz (334x9)
2x1GB Ballistix DDR1000 @ DDR888 3-3-3-9
MSI 8800GT 512MB OC
Creative labs Audigy value sound card
2 x opticals (1 cd burner and 1 DVD burner)
3 HD's (80G, 160G, 500G)
6 x 120mm fans

Using my Fluke Meter I measured my voltage at the outlet and the current my tower draws at idle and at load. Idle was while sitting here typing this thread and load was measured while running Orthos, scanning for viruses, playing music, running 3DM'06 all at the same time. I figure thats about as much load as this thing would ever see. :D

The voltage at the outlet is just under 120V, we will just use 120V. The current draw at idle is .99amps. 1 amp for short. Under load, the current draw was 1.97 amps. 2 amps for short.

Watts = Voltage x Current
so at idle my system uses under 1 x 120 = 120 watts.
Fully loaded it uses about 2 x 120 = 240 watts. :eek: OMG!!! 240 WATTS :rolleyes: (it was about 1.85amps x 115V actual = 212.75 watts while playing COD4)

So there it is. this: http://www.tomshardware.com/2008/04/01/nvidia_geforce_9800gtx_review/page12.html
Seems to back up my findings very closely. Anyways. I hope this will help people decide when buying a psu. Especially if thier on a budget.

If I tossed in a quad and ran sli I bet I could break 300 watts... hehe

Thats why I say "I want to see the system that NEEDS a 1000W-1200W psu" hehe SHOW IT TO ME!!!!

[[Jett]-CRX]

The total wattage of the supply isn't the point. The technical limitation of the older power supplies is the way the current was divided into rails with current limits (18A @ 12V, etc) on each rail. Overloading a particular rail (say, putting your honkin' new CPU and that fancy graphics card that had it's own power connection), etc. on the same rail could overload a single 12V rail. This would cause the entire power supply to turn off. (I know this from experience... I've been there.)

CPU manufacturers who recommend 500W power supplies, etc... are really trying to ensure that the 12V rail has a high enough circuit protection limit to provide the necessary power to run that particular chip.

For the most part, newer power supplies have abandoned these constraints, and the designs, which don't REALLY conform to the safety requirements of the ATX standard, are being approved by the UL anyway.

See http://en.wikipedia.org/wiki/Power_supply_rail#Multiple_.2B12V_Rails for a more detailed explanation.

[[Jett-R]-Giant]

Yes, you are correct. It is better to buy a single rail psu. hehe :)