Hi all, Basically I've got a really bad issue with this system I purchased from OCUK. I got it a month ago and its still not working, It continually reboots for no reason, I've had over 5 IT pros looking at it stumped and we cant seem to narrow the problem down at all. I was just wondering if anyone here may have some other ideas, or may have experienced a similar problem with similar hardware. Ill list out everything that has been done to the machine carefully so if you are going to post up a reply please check what i have written first properly, because I'm pretty tired of answering the same old questions and going round in circles! thanks in advance and a postal order for 2 pints will be heading to whosoever can help me in this time of need (unless you are in or around london in which case ill have to take ya to the pub.) heres the spec! Gigabyte GA-N650SLI-DS4L nForce 650i SLi (Socket 775) Hitachi Deskstar 7K160 160GB SATA-II Samsung SH-S203D 20x DVD±RW SATA Dual Layer ReWriter Akasa AK-965 CPU Cooler Intel Core 2 Quad Pro Q6600 "Energy Efficient SLACR 95W Edition" 2.40GHz PNY GeForce 8800 GT 512MB GDDR3 Hiper 530w HPU-4M530 SLi Certified ATX 2.2 PSU OCZ 4GB (2x2GB) PC2-6400C5 Dual Channel Vista Gold Series DDR2 I spent weeks double checking the compatibility of these components and as far as i could see i made a pretty nice little bundle (well i guess not but hey..) -- I got the machine, mounted it up and installed XP x64. This is when the reboots began... My machine reboots for no reason at all when; installing stuff, running games, transferring data or sometimes for no reason other than clicking a continue button. so first test.. i removed the PSU and plugged it into a similar machine it ran fine.. i then took a different PSU into my system and the reboots continued. at this point x64 was useless so i proceeded to try xp 32bit. this was more stable and i was able to get the os installed.. so i ran Company of heroes and 3d studio max renders to give it a work out.. the reboots continued. i removed the ram (replaced with other different make ram) i also tried all the slots with one and two sticks and ran the memory through memtest and it all checked out fine.. i removed the hdd and the dvdrw and installed two others and tried installing the os onto that still rebooting i also ran a load of low level checks and the hdd is fine.. finally i tried putting a different video card and processor in the mobo and still the reboots persisted (i also tested my processor and 8800 in the other machine and they work fine.) so now i sent the motherboard back to OCuk.. and lost 17£ for the pleasure because it came back fine. after it came back i tried flashing the bios with an update and installed a new version of xp 32bit and still the problem continued (at this stage i should point out that i had mounted the machine outside the case aswell). so i tried loads of more combinations re running the same old tests until i had come full circle.. i then tried swapping out the cmos batt because i read on another forum that a low juice batt can cause intermittent reboots (still no joy) so i called OCUK again.. and i was told 'yeah it does sound like the motherboard.. send it back and when it does fail we'll reimburse you' .. but it passed 39hours of prime95 testing so hey great.. back to square one. i got it back the other day (Minus my only IDE cable so thanks for that OCUK i hope you are enjoying it.) and tried to install vista. I cant even get it to run all the way through the setup.. i am now at the end of my rope.. its been a month.. I need this machine to do work.. I have had to pass up 2 jobs and I also have a degree to finish. I purchased a machine for over £700 and it doesn't work.. so I'm really hoping that someone here may have another idea for me.. TBH i am sick of it and have no faith in this hardware and am really at the point where i dont really want it anymore, but ill give it one more chance because when it is running (for the few mins ive been able to get it up and running) it is a machine of power and beauty.. If anyone on here has some ideas about what else could be causing this apart from my parts just being totally incompatible with each other then i will be much appreciative!!! waiting in hope! Josh P.S. its not overheating, in fact i was monitoring the temps in speedfan when i had xp on there and its cpu is running at <30 degrees idle and the graphics unit idles at about 48. and no .. there are no heat spikes.. Also .. i have no intention of overclocking the system and have not attempted to do so because I just want something stable for now.