Pop open the PSU and check the caps. A blown cap (or one in the process of blowing) is very apparent.
Constant long beep = make sure you plugged the power into your 9600 when you switched. Other constant beeps are cannot find usable memory (different than 3 beeps where the first 64kb cannot be found), video card installed but not usable (same as other, different than 3 beeps where there is no card installed)
You could also be underpowering your system on the 12vt rail. Regardless of how much power the PSU can provide, it might not have enough juice along the 12vt line. Whats the amp rating on 12vt?









