Today I completely upgraded my computer by replacing the motherboard and everything, I had my relative's help with instaling the whole thing, but I'm having problems with it. When I boot up my computer, it does the normal load up, but sometimes it stops loading, sometimes it freezes, or sometime it turns blank screen and my power and reset button stops working. I have never seen this problem before, can anyone help?

Post back with some specs. We need to know the mobo make and model, CPU speed, PSU output, etc. Then maybe we can work out your problem.

It's KT333 VIA motherboard http://www.soyo.com.tw/products/proddesc.php?id=58 Cpu is Athlon XP 2000, I'm not sure what PSU output is. 350watt power supply, 6 total fans in the system(5 in case, 1 for CPU), HP CDwriter 7500i serie(primary master), and two hardrives (secondary master/slave). That's all I can come up with now, if more information is needed I'll post it.

The PSU (Power Supply Unit) output of 350W should be enough, although it may be faulty. See if you can borrow another PSU to try in your machine. You might also like to try disconnecting your CD writer and slave hard drive and see if it will boot. If so, connect these devices one at a time to see if one of them is causing the problem.