BSOD during boot after switching memory modules

[phobic]

For my new build I made the rookie mistake of ordering parts in advance when I saw a good deal, and having prices drop even futher by the time I got the full build setup. I built with the first set, because the new one had to be RMA'd for shipping damage. Everything was working fine with that in. The new set just arrived today, so I went to swap it out and do some testing to figure out what my final setup would be.
old: F3-12800CL7D-4GBRM
new: F3-12800CL9D-8GBXL

I swapped the modules out and went to boot, pressing DEL to get into BIOS to change the dram config. This is where the problem started. BIOS never loaded, it just hung on the startup screen. After a hard reset, the computer powered up, but nothing happened. It just stayed at a blank screen. At this point I swapped the modules back to the old ones and tried to boot again. I can now get into BIOS, but no matter what settings are used, I get a BSOD shortly into the windows startup sequence. This now happens with all of the memory modules, old and new. Clearing CMOS didn't work, safe mode doesn't work. Memtest from a bootable flash drive returned no errors on either pair, but I just read on the forum I need to run it on single sticks, which is in progress now. Moving them between slots also didn't work. I'm well and truly stumped. My next plan is to see if there is a BIOS update for my motherboard, but since it worked fine right before the swap and now doesn't even with the same configuration, I don't hold out much hope for that. So.... ideas?

specs:
Intel i7 2600k
Asrock p67 extreme 4 gen 3
HIS AMD HD 6950
OCZ ZX 850W 80+ gold
LG black super multi BD burner
Creative x-fi xtrememusic
Seagate barracuda 1TB (ST310005N1A1AS-RK)

[Tradesman]

Check on the BIOS update , if needed go ahead and flash, then try with the preferred sticks, if you can get into BIOS, enable XMP and select the 1600 profile....am sort of thinking when sticks were changed it may have corrupted the Win install..if that's it can do a repair from the Win DVD

[phobic]

I've already tried both auto and XMP settings on both pairs, so that's not it. I thought about a repair install, but put that in the 'desperation' column of my things to try list, right above RMA the motherboard for fried RAM slots (which doesn't seem likely, given that I can memtest with no errors). I'll get back with the results of bios flash/repair install. It might help if I could actually read the BSOD error :/

[Tradesman]

Let us know what happens, the BIOS updates have been hot and heavy on P67 and Z68s (and likely will increase with the release of the 8GB sticks and Sandy Bridge E sets, many mobo makers are still trying to catch up

[phobic]

well, SOMETHING finally worked, but I don't think it was the BIOS update. It failed to boot once more after updating. But I went messing around in BIOS again and maybe reset something back that I missed the first 349 times. Right now I've got the old pair in. So before I make the swap and potentially start the whole thing over again, let me ask, do I need to swap the DRAM settings in BIOS to auto BEFORE I change out the memory, or does it not matter as long as I load BIOS and do it the first time?

[GSKILL TECH]

Either way, as long as the computer posts so you can change BIOS settings. If you have settings completely off, the computer will not POST, so you would need to load BIOS defaults, or reset BIOS on the motherboard. Once it is default, AUTO, then the system should boot no matter what as long as the memory is indeed compatible.

Thank you
GSKILL TECH

[phobic]

All seems to be well. One last question unrelated to the errors. Initial tests indicate a not-insignificant performance loss from the CL-7 to CL-9 sticks. Can I try raising the voltage and tightning the timings on the 8 gb pair without voiding the warranty?

[Tradesman]

That would be an option, maybe up to 1.6....another option to tighten timings would be to drop to 1333 and then start at CL8 (say 8-8-8-24) and tighten from there, may be able to hit CL7 @1333 which would offer better performance than 1600 CL9 native