Is 400W Really Too Little?

Hello! I am back, for those of you who saw/or posted on my previous thread about a super budget build. However, the tides have turned and I now have a significantly higher budget. Previously, I only had $250 (gasp!) and with a little persuading have managed to get a good sum of extra cash to use. I am at a current budget of around $500.

Straight to the point, I want to build a machine with an AMD Athlon 7850 Black Edition (2.8GGz + 2MB L3 Dual Core), 4GB of DDR2-800, and a 9500GT Video Card. Power supplies, however, is where I get stumped. I used a power supply calculator and it told me I only needed about 270W or so to power the system! But after research, I see people with similar systems using 500 to 750W PSUs. Are they insane or am I under estimating my wattage? I would like to use a Corsair 400W PSU: http://www.newegg.com/Product/Prod [...] 20corsair.

Would it be enough?

Thanks a lot, (again)!

I just checked several references I have bookmarked. The 9500GT (256MB) video card is not a power hungry card like some of the others. The atomic web site shows a power consumption range between 19 and 35 watts. The rest of your budget system will not use much power either. The Corsair is an excellent high quality psu. The +12 volt rail is rated at 30 amps. It can definitely handle your system. No problem.

The higher wattage psu's are for high end gaming systems. A high quality 500 to 550 watt psu is designed to handle just about any single power hungry video card made. High quality power supplies rated at 750 watts and above a designed for high end gaming systems with mutiple video cards. They are for those seriously overclocked quad core systems operating in SLI or Crossfire mode.

HD4650 has better performance for the same price.

The 400W is definitely sufficient, though as theAnimal said, the HD4650 will perform better than the 9500GT for about the same price.

Yep...it'll be my multi-purpose everything computer. I will be doing all of my work (mostly word processing and presentations), watch movies, playing back my music, some gaming thrown in there, and some 3D work and rendering.

But, right now I am running off an Intel PDC 1.6GHz 1MB L2 Mobile Processor and it does pretty well with all of these applications...but I thought I should get a new system that might do these a good deal faster and more efficient.

The 4650 is considerably faster than the 9500GT, though I'm not sure about power consumption. There should be quite a few benchmarks/charts on the web in regards to that matter.