Correct me if I am wrong but in your post you said(quote) i noticed that in system i had 6gb of ram but only 4gb usable, so i checked the resource monitor 6144mb installed ram - 2gb hardware reserved 4gb available. If the slot was dead it shouldn't read the memory to know how much was in it. It may be worth trying running CPU-z. The spd tab will let you know if the ram is seen in all the slots.
A dead "slot" sure, but "faulty" RAM can do some very odd things. I just returned some OCZ Platinum that had gone totally feral, it was in DDR3_3 yet showing it was enabled in DDR3_2 (which of course was empty), and yes it would happily inform Windows it was present, however it would of course not work any which way, and if booted in DDR3_1, would fail to post. Memtest sensibly rebooted itself as soon as it walked the 1st byte of it
Ram can do odd things
A bit more info,
i have now installed 12Gb of Ram, Cpu-z does shows 2Gb of ram in each slot but the resource monitor now shows 4096mb hardware reserved with 8192mb available, in 'System' it reads 12GB installed with 8GB usable , am having trouble installing memtest so cannot test memory with that.
i tried each stick of ram in dimm 1 but could not even get to post screen on startup, did the same in dimm 3 no problems went straight to post screen on startup.
What is the problem with memtest?
Burn the ISO and boot with it... or if you have some linux CD's around (Mandriva for example) many of them have memtest as part of the start up routine which may be selected
Hrmm... Certainly sounds like a slot issue if you are saying none of you six chips will boot individually in DDR3_1 and yet work in DDR3_3, although as a previous poster said this is odd given the RAM is being "seen" by Windows, CPU-Z (and I presume BIOS itself to some extent).
God what bad luck to have damaged the board somehow.
Can you confirm that none of the chips are booting at all in DDR3_1 (2nd slot across from CPU)