Hi,
Firstly, make sure the RAM is running at the correct frequency, timings and voltage as recommended by the manufacturer. Run your RAM at the factory settings i.e. SPD or AUTO. Reset the CMOS if you have to then retest.
Run memtest86+ . THis will show you if you have RAM related problem but this doesn't mean the RAM is faulty. It could be the Integrated Memory Controller (IMC) is faulty which is located on the CPU for newer Intel models. You'll need to find out which or which modules is faulty if that is the case..
If the memtest still shows errors then test using one memory stick at a time in the same slot. If one stick fails but the others do not then you have found your faulty stick.
If however, all sticks fail or pass then repeat the test in another bank/slots. If the RAM works in one slot but not the other then this is certainly going to be a problem with IMC.
I have a memory troubleshooting guide here:
http://forums.overclockers.co.uk/showthread.php?t=18261596
If your memory looks ok, then you may need to check your PSU:
http://www.huddysworld.co.uk/index....rdware/91-hoe-to-check-if-your-psu-is-working
If you can boot into your system via safe mode, then take a good look at the system dump and Event Manager for clues. Event manager is often overlooked and under estimated.
Make sure your drivers are fully upto date.
Hope that helps
