Windows 7 - RAM Issues

Hello,
I have 2x2GB Micron 1066MHz DDR3 RAM in a p67 board.

I CAN boot with module A in ANY slot on its own
I CAN'T boot with module B if its in any slot on its own.
I suspect module B is broke.

When:

No modules installed = boot black screen for 10 secs then crash

Module A is in slot 1 and B in slot 2 = FAIL TO BOOT
Module A is in slot 1 and B in slot 3 = FAIL TO BOOT
Module A is in slot 1 and B in slot 4 = FAIL TO BOOT

Module B is in slot 1 and A in slot 2 = BOOT
Module B is in slot 1 and A in slot 3 = BOOT
Module B is in slot 1 and A iin slot 4 = BOOT

Module A is in slot 2 and B is in slot 3 = FAIL TO BOOT
Module B is in slot 2 and A is in slot 3 = FAIL TO BOOT

Module A in slot 2 and B in slot 4 = FAIL TO BOOT
Module B in slot 2 and B in slot 4 = FAIL TO BOOT

Memtest with just A in slot 1 = PASS 100%
memtest with A in slot 1 and B in slot 3 - PASS 100%

I'm really stuck here, any help?

You will need to run memtest on each stick in each slot for any definite answer. One stick per test, per slot, 8 full passes unless you get any errors.

Thing is I can't boot with just B on its own, so I can't test that individually.
However A passed on its own, and on a test with A+B I had a pass also

By boot I mean I can;t even reach the post screen (sorry if I wad unclear)

OK, memtest has a bootable version too, which can be burned to a CD Memtest86.com - Memory Diagnostic Click Free download, it is free.

There should be a MEM test in the boot screen

I have one on my other board so im sure yours might have it too

Good point Tommy, but it is in windows Repair options screen, accessed by holdin F8 during boot. May not work here with the possibly bad stick.

No I meant I could not even get the BIOS screen (POST) it would turn on for about 1-2 seconds then crash, then attempt to boot once more and crash in an indefinate loop.

Strangely soon after this, module B failed to boot in any configuration which means it must of finally died.

What worried me however is that it passed memtest86 just before, is there an explanation for this?

regards, Jamie.

Well, I guess there could be several reasons. But memtest86 is the best test we have for memory, but it is not perfect or absolute.
I am not familiar with Micron ram. But, most manufacturers test ram to be run as a set. In other words, tested the sticks to run together. I would suggest that if you RMA the stick that you RMA the set so you will be returned a set tested to be run together.
I don't know the specs on your ram, but Sandy Bridge is made to run on 1.5V ram. Yes, other voltages can run on SB, but it is designed and works better on 1.5V with little to no tweaking.
If you haven't already, I suggest you look up the ram QVL list for your board. These are only the ones they have tested. Other versions will work. What I do is look for my brand and pay attention to the voltage, frequency and timings of the ram they tested from that manufacturer. I then use that criteria to pick out ram which usually works with no problem.
That's about all I know to tell you. Some boards are just particular about ram and have problems running certain kinds of ram when there is really nothing wrong with the ram itself.

I hope your right. My RAM is not on the QVL, but I still don;t get how one stick had problems and the other didn't, maybe its bad luck.

I ran memtest on the working stick and got 3+ passes in all 4 slots and the RAM is working fine, so I've sold that stick to someone and ordered in 2x2 GSkill RipjawX's.

Hopefully i'll have no problems now, so i'll mark this as solved.

thanks all for the help

I don't know how much I've helped, but I wish you good luck. Come back and let us know the results.