Trouble After Changing the Multiplier

Hi, figured I'd post here, I'm desperate for help. After reading around, I fear I did something horribly stupid and nooby and am looking for some damage control.

I built a $1000 rig for a relative and have run into some issues, one that stands out at the moment:

I was tweaking some BIOS settings when something apparently went wrong. The only non-default settings were changed by the OC Genie (of my MSI board)... I was going to change the multiplier from x16 to x18, which would bring my AMD Phenom II X2 555 BE to around 4.1-4.2. When I exited & saved settings, and it rebooted, I got nothing. The fans turned on, but I got no video feed (monitor is stuck in sleep mode). I've tried rebooting sever times and just depressed the physical OC Genie button (in theory resetting the OC'd settings), but no luck.

I guess I want to find a way to reset everything without having to go into BIOS (which I can't do), or whatever else would fix this.


...on a side note, I've been getting random BSODs. I unlocked my X2 to be an X4, but since then I've been getting random screens (which appear to be random). I've had Prime95 running for several hours, and stress doesn't seem to correlate to blue screens. Since then (and before the problem described above with the multiplier) I've disabled the Core Unlocker.

If it sounds like something is physically wrong with my CPU, I'd like to know what, and what I should do about it (RMA, etc).

Thanks for any and all help.

Build:

AMD Phenom II X2 555 BE Callisto (air-cooled, stock fan)
MSI 870A-G55 motherboard
EVGA GeForce GTX 470 (stock settings)
Corsair 64 SATAIII SSD
WD 320gb SATA III
X-Power Pro 600W PSU