Overclocking CPU issue or Memory issue

[themanwithnoname]

I'm been fiddling with overclocking all weekend long and its starting to get to me . So pretty much out the box I set my 555be at 4ghz @1.45v and for the most part it seemed pretty stable. I ran small ffts on prime and it wouldn't get an error or anything. But now i'm getting problems with running prime on blend. Like it will run fine for as long as 4 hours but then go kaput and bsod and reset. no rounding error or anything. I have my memory set at 800mhz 8:8:8:24 @1.65v this is stock. Heres my prime95 results log from last night.

[Sun Feb 28 01:56:45 2010]
Self-test 1024K passed!
Self-test 1024K passed!
Self-test 1024K passed!
Self-test 1024K passed!
[Sun Feb 28 02:12:15 2010]
Self-test 8K passed!
Self-test 8K passed!
Self-test 8K passed!
Self-test 8K passed!
[Sun Feb 28 02:28:29 2010]
Self-test 10K passed!
Self-test 10K passed!
Self-test 10K passed!
Self-test 10K passed!
[Sun Feb 28 02:44:38 2010]
Self-test 896K passed!
Self-test 896K passed!
Self-test 896K passed!
Self-test 896K passed!
[Sun Feb 28 03:00:47 2010]
Self-test 768K passed!
Self-test 768K passed!
Self-test 768K passed!
Self-test 768K passed!
[Sun Feb 28 03:16:53 2010]
Self-test 12K passed!
Self-test 12K passed!
Self-test 12K passed!
Self-test 12K passed!
[Sun Feb 28 03:33:03 2010]
Self-test 14K passed!
Self-test 14K passed!
Self-test 14K passed!
Self-test 14K passed!
[Sun Feb 28 03:49:17 2010]
Self-test 640K passed!
Self-test 640K passed!
Self-test 640K passed!
Self-test 640K passed!
[Sun Feb 28 04:05:10 2010]
Self-test 512K passed!
Self-test 512K passed!
Self-test 512K passed!
Self-test 512K passed!
[Sun Feb 28 04:20:53 2010]
Self-test 16K passed!
Self-test 16K passed!
Self-test 16K passed!
Self-test 16K passed!
[Sun Feb 28 04:35:54 2010]
Self-test 20K passed!
Self-test 20K passed!
Self-test 20K passed!
Self-test 20K passed!
[Sun Feb 28 04:51:59 2010]
Self-test 448K passed!
Self-test 448K passed!
Self-test 448K passed!
Self-test 448K passed!
[Sun Feb 28 05:07:22 2010]
Self-test 384K passed!
Self-test 384K passed!
Self-test 384K passed!
Self-test 384K passed!
[Sun Feb 28 05:22:41 2010]
Self-test 24K passed!
Self-test 24K passed!
Self-test 24K passed!
Self-test 24K passed!
[Sun Feb 28 05:37:56 2010]
Self-test 28K passed!
Self-test 28K passed!
Self-test 28K passed!
Self-test 28K passed!

So my real question is how to tell if this is a memory issue (which i think it may be) or a cpu issue. i guess the most obvious and practical thing to do is to either overclock the cpu and drop the memory below stock settings and run prime on blend and see if it works. Or to run the memory at stock and underclock the cpu.

I've also noticed that my 12v rail really drops at load. sometimes as low as 11.14V. I'm running a enermax eg465p-ve 431w psu. i ran the extremepsu calculator and input my setup and at 100% load w/ 30% capacitor aging (psu is more than 5 years old) it came out to 544W. also i don't know if this helps but when its under load i can hear the fan speeds go up and down. guessing thats not good?

i've also ran memtest for windows for a little longer than 1 hour with 35% coverage w/ 0 errors.

Thoughts?