BSOD when after 4gb to 8gb upgrade

Intel 5 series motherboards have some issues when going from 4GiB or less of physical memory to over 4GB of physical memory. Normally this manifests as the second 4GiB not being seen but I suppose other bugs are possible. This is fairly easy to fix

Step 1. Update the firmware to the latest revision. Many motheboard manufacturers improve memory support after the board's initial release

Step 2. Perform a complete flush of the firmware (BIOS/EFI) settings. Do not simply pull the clock battery, consult the motherboard manual for the proper procedure. After doing this you will have to restore any non-default settings that you had configured.

If those do not fix the issues, bump the memory voltage from 1.5 volts to 1.55 volts. This is still within the JEDEC specification and may compensate for a crummy PSU or voltage regulator.

What version of Memtest are you using?
I prefer Memtest86, that requires a clean boot. If you're using a Windows based one, it probably can't access all of your RAM.
Let Memtest86 run over night (more than 1 pass) and see if it has errors in the morning. If it does, RMA your new modules (assuming it is a kit).

Thx for the info
Was Memtest86, but only 1 pass...ill try more than one pass...if this doesnt work, ill try Pinhedd solution
Thx again

not in my experience

agreed with the solution however

also force memory to 1066 @ 1.55v see if that has any effect

I've seen the 4GiB -> 8GiB = 4GiB missing issue numerous times and every time the same solution works. It seems to plague the Intel 5 series chipsets for some reason. I believe it has something to do with the mapping of hardware addresses for compatibility with non-PAE kernels and/or DMA