New power supply/PC won't boot

Hi, I have recently built a new PC and about a month after completing it my power supply started to make a burning smell.  I immediately turned the computer off so the issue is not that the old one blew out.  I put a new one in and now my computer completely fails to boot up.  The fans start to go and everything just nothing shows up on the screen, it says that there is no signal.  Also, I cannot turn it off by the power button, I had to flip the switch on the back of the power supply.  Maybe the problem is that the PSU is 20 pins and my mobo takes 24? I thought that didnt matter though.  Please help, I'm getting really pissed off.

You may at least want to get a 20->24-pin adapter.

The PSU is one of those parts that you might overlook since it doesn't noticeably improve performance (but I'm sure someone will say it does) but it's really really important that you get a good one.

I've always stuck with Antec PSUs when I care about the machine I'm building (okay, so there's only 2).

Get a 24pin PSU.