This may fall under the "dumb question" department but I'm putting together an older PIII 500 system for my daughter and I need a new PSU and was wondering if a modern 400 or 450 watt PSU would be too much power for a PIII or perhaps wouldn't work properly. Anyone know if there is any truth to this? Thanks Asus K8V-X Athlon 64 2800+ ATI AIW 9600XT 512 PC3200 WD 80 GIG HP CD-RW LG DVD Send me your unwanted computer parts!

It does not matter how many watts the psu provides. Provided more are available than actually required. Think about your house. If in the Uk the lighting circuit supplies 220v with a 5 amp fuse. This will not blow until (5 x 220) >1100watt is reached. Now you can turn on just one 40w bulb or whatever without problem. Provided the psu is suitable for and fits your mobo there should be no problem. Good Luck - Keep us posted.

The system will only use the power it needs...you won't be shoving 450w down it's throat. Your PII or PIII should work just fine with a modern psu. Skip

Thank you for your quick replies! :) Asus K8V-X Athlon 64 2800+ ATI AIW 9600XT 512 PC3200 WD 80 GIG LG DVD-RW XP Home Full time employee of Dharma. One of the "others".

The only thing you need to be concerned about is whether the main connector from the new standard ATX PS has the same wiring as the one originally connected to the PIII 500 mboard. If the PIII 500 mboard was not in a brand name computer system and is not a server mboard, chances are nearly 100% it uses standard ATX wiring; if it was in a brand name system there is a tiny chance the wiring of the main connector is proprietary, that is, non-standard; if it is a server mboard there is a very good chance the wiring is proprietary. In the latter two cases, you may need to get a new PS that has a main connector that is wired non-standard, or use a wiring adapter to adapt a standard ATX PS to the mboard main connector. Many recent power supplies can be used on mboards that have either a 20 position main connector, or a 24 position main connector, by means of a one piece 20 position main connector, and a 4 pin connector you can place beside it if needed on mboards that require a 24 position connector. The wiring of the one piece 20 position connector is identical to that of power supplies that have only that connector and no provision for the 24 position connector on the mboard. The wiring colors are standardized and relate to standard uses at these main connectors. The colors of the wires at the same positions in the main connector, and the numbers of wires at each position (some positions have two wires), must be identical for both the PS originally connected to the PIII 500 mboard and the new PS. You do not need any more than 250 or 300 watts for the PIII 500 mboard. Some 300 and 350 watt ones are still available. Just don't buy an el-cheapo PS - it should be a brand with a good reputatation, it should have at least a one year warranty, or better, a three year warranty, and it should have anti-short and overvoltage protection built in.

Mike Newcomb Just an aside regarding your explanation in #1 (which I thought was very well put). Being very pedantic, in fact the Amps marked on any fuse is its "rating", ie it will carry 5A without blowing. The current level which causes it to blow will depend on the type of fuse (it's characteristics) and time. It can sometimes require more like 10A to rupture a 5A fuse. I'm from Kent UK btw. DerekW

Have an e-machines 400 Mhz machine from 1999. Power supply failed after six years and I got a new one from NewEgg.com $20, and works fine.