My system can't pass Prime95 on stock. Need help.

My system wont pass Prime95 (Blend test) even on stock..

I got..

Asus A8N-SLI Deluxe
AMD FX-55 @ 2.6
2 gig DDR 400 RAM

I've had this comp for years now but now that I've started over clocking for fun I've realized my set up cant even pass Prime95 with stock speeds and timings. I can pass Small FFT's test after I upped the vcore a tad but I can't pass the blend test for the life of me..

I've tested my RAM with Memtest over night for 9+ hours and no errors. So RAM seems fine...

I've, like I said, passed small FFT's test so CPU seems fine... (Ran over night 9+ hours)

I've played around with vcore quite a bit.. Currently at 1.45 which is the voltage I pass Small FFT's at. I've tried upping it to pass the blend test but that just seems to be overkilling it and brings issues. At certain voltages my motherboard chip will jump up 10 degrees out of nowhere. (Using Speedfan for temp readings) Sometimes I can go even higher voltage and motherboard will jump back down to a normal temp increase of a degree or 2. So I dunno what the hell is up with that.

I mean, whats the deal here? I've had my machine for years now and its always run fine but I'd still like to try and help it pass this test.. Any ideas?

Yeah, try significantly underclock the ram, and run test to see if it's really cpu's fault.