Are these memory sticks different? (among other things..=)

Hey Hey

I've had computer problems for over a year, and while testing individual memory sticks I noticed the following:

DIMM1: Kingston 9905402-018.A01LF
DIMM2: Kingston 9905402-018.A01LF
DIMM3: Kingston 9905402-020.A00LF
DIMM4: Kingston 9905402-020.A00LF

The only other difference I can spot in Everest is "Manufacturing Date"
Week 10 / 2008 (018's)
Week 13 / 2008 (020's)

My computer freezes (no BSOD) and I have to reset manually. It happens during rendering in Maya, during regular gaming (even during booting of games), and sometimes when I just browse the web).

System:
Motherboard: XFX Nforce 790i ULTRA (Bios p08)
CPU : QX9650
Memory Kingston HyperX DDR3 1600mhz, CL9 (9x9x9x27). FSB Linked & Synced, P1 & P2 Enabled.
GPU : Radeon 5870 (Switched from 9800 GX2 the other day, but the problem still persists)
Sound : Onboard. (I have an X-FI, but it's about to go out the window)
All my temps are well within reason.
OS : Win7 RC, but the same thing happens in XP, Debian and Fedora.

The memory sticks have 1.9v marked on them, and my bios auto's to 1.5, I've tried 1.6, 1.625, 1.675, 1.7, 1.75 and 1.8, all deliver the same result. I've messed around with the timings, and as far as I can remember they are set to 8x9x8x25.

Everest reports:
Memory Speed DDR3-1066 (533 MHz)
Memory Timings
@ 533 MHz 7-7-7-20 (CL-RCD-RP-RAS) / 27-59-4-8-4-4 (RC-RFC-RRD-WR-WTR-RTP)
@ 457 MHz 6-6-6-18 (CL-RCD-RP-RAS) / 24-51-4-7-4-4 (RC-RFC-RRD-WR-WTR-RTP)

I can post my entire Everest report if that might offer more clues!
Anyways, thanks in advance for any and all help!