thx for ur suggestion guys
my dimms passed the memtest86+ #5 tests, had it running both for an hour.
i have noticed something strange while trying to boot from the memtest86+ cd.
i booted from the cd and it said "Loading....." and my system froze, had to reset by hard reset as crtl+alt+del didnt work.
i went straight into the
bios and disabled AHCI and NCQ, to see if that was the problem.
cd booted and tests were error free.
this is what i had in mind after i had the booting problem from cd (
sata rom) with the intel controller running as ahci with ncq
quite alot of work but seems like i have to do it again

i build the whole system myself and it was making sure i didnt have any shorts. who knows maybe i missed one spot.
by the "check the I/O shield" u mean the backplane with usb, audio/video connectors?
it happens only if the system was shutdown for a longer period of time.
i shutdown my rig before i go to sleep around 11:30pm. i wake up and before i leave for work im checking for new mails around 6:50am and the problem occurs. its pi**ing me off

.
once i've checked my mails i shut it down leave for work and around 5:30pm i turn it on again just to get pi**ed off by the problem again

it never occurs a second time after i have reset the system once the freeze happens
i can game, encode, watch shows/movies using media center etc without freezes. its just the very first time i start the system after it has been shutdown for more or around 6 hours
yeah but its really weird that it does not happen when the system was shutdown for 1-2hours. something must be "unloading" that takes alot more time, like overnight.
i checked and redid the whole cabling a few days ago. no contact with other parts. i havent re-mounted the cpu fan yet as its quite heavy and hard to mount, i guess by CPU HSF u mean heat sink fan?