im having problems with pc shutting down randomely i have replaced psu motherbord checked cpu and ram also replaced case i am watching temp very closely and it still shuts down this is just the set up my real question is i reused ram dvd burner and hdd i would like to elimanate this being a software issue and reinstall vista after reformat but vista came with no disk will microsoft supply me with a disk i bought this acer at circuit city 2yago i can provide receipts and authentication code from side of case iam worried that if i make recovery disk that whatever problem if any would present itself again i would like to atart fresh with clean drive

Well you could have bought a faulty MB or if you didn't replace the CPU or RAM there could be a problem with either. A DVD burner isn't likely to shut the PC down. That leaves your hard drive which is more likely to cause a problem. Now does the computer just shut down normally (in other words the user is logged off and you get a screen saying that it is rebooting/shutting down), do you get a blue screen of death, or is it just restarting/turning off without shutting down? If you come to your computer and it has shut down it could be that in the power options it is either set to go into stand by or to hibernate after a certain period of inactivity. To check this go to control panel, power options. Click on the change plan settings link underneath the plan that has the filled in circle and then select change advanced power settings. Look for sleep and hibernation.

Now for one thing, because of the way windows is set up it must be reinstalled after buying a new motherboard. It could be that windows is the culprit so if you reinstall, and you must, that might fix the problem. Another thing to check is whether or not you have a powerful enough PSU. Use the Extreme power supply calculator and plug in your current system's specs which, by the way, we need to know. If you are still using the same RAM that could also be the problem. You need to have it tested [I don't know of a good memory tester but someone else will]. You should also go to the drive's manufacturer's website and download the file for a bookable diagnostics disk.

I know you don't want to but I would start with an OS reinstall since your system needs it anyway. If need be you can buy an OEM version of Vista off of Newegg for cheaper than retail or you can try to contact the manufacturer and see if you can order a replacement disk. If this is a name brand computer (such as HP) then your drive might also have the recovery files built into the drive. From computer look for a drive other than the C drive or your dvd drive. If you have one then it is probably a recovery partition especially if it pops up a screen warning you about changing the files on it when you double click on it. If you do have one how you access it depends upon what the manufacturer is. You can start by checking the manual. Unfortunately I don't know if it can be accessed from a motherboard other than the model that the manufacturer makes. Actually if you replaced the MB with one other than the model that came with the computer a recover partition or recovery disks would not work so in that case you would have to obtain a new disk.