What is the minimum power supply wattage needed for a Pentium 2.4GHz system?

"Try this tool which helps you calculate the right size

http://extreme.outervision.com/psucalculatorlite.jsp

Sometimes it's worth paying a little more for a more efficient one."

"Not saying it wouldn't work, but 200W does sound a bit low. Personally, I would rather have one that is above what you need and leave it at 50% capacity than getting a low one and running it at 90+.

I build many machines and even with loads of hard drives, graphics cards and more, I have never needed above 550W and for most machines, I use 400W"

200w may not suffice for a 'northwood space heater' at full CPU load, even in combination with a very low spec graphics card.

I just did a full install of Xubuntu 10.10 with a 2.4ghz P4, 512mg PC3400 DDR, 40gb Sata drive, IDE DVD drive, running a wireless card and stock graphics (Intel 865glc board). I unplugged the case fan and didn't work the system hard after the install, but it ran Firefox etc. just fine. I think a bit of the big number power supply game is over rated, the 120 watt I had came with a P4 plug so I figured I might as well give it a shot (it is TINY, from a little bitty PC, but it was the only PSU I had out of 6 that didn't have dead caps!).