How can I use older PSU with a new motherboard

[shishir]

Hi guys, I am upgrading my P4 (478 mPGA) computer to either LGA 775 or LGA 1156, depending on my budget (still not decided). My current system has a 20 pin ATX 2.03 PSU - 400 Watt with additional 2x +12V and 2x Ground placed in a shape of square (in 2x2). I was thinking whether I can use this with MSI H55M-E33 (H55) and Gigabyte GA-G41M-ES2L (G41) motherboards? If it is possible, then what are its pros and cons?
If not possible, is their any way I can use my current PSU using some additional brackets or something?
THANX in advance.

 

[Lmeow]

Some motherboards can still work with just a 20-pin power connector. However, it's possible that the board may not be receiving enough power. Also, with older PSUs, most of the amps are on the 3.3V and 5V rail, which mean if you do intend to use a graphic card, you'd need something which uses very little power, due to less amps supplied on the 12V rail which supplies the power to both the CPU and graphic card. Thus it'd be safer not to overclock either.

 

[megamanx00]

Most newer boards will work just fine. There are a few boards that may not boot with a 20pin PSU (rare but it happens), but you can simply get an adapter for that. Of course, as Lmeow said older PSUs tend to have less amps on the 12v rail. Also, as PSUs age they are generally less effective. If you want to overclock or use a high end GPU (or even a midrange one) you will need to upgrade the PSU.