I had a simlar problem a while ago, but it was with an older mboard.
It turned out one of the ram modules was incompatible with the mboard chipset and it was causing ram errors, and reboots for no apparent reason, but only when more than one ram module was installed.
Ram that works in another mboard , or any ram you buy or have lying around, may not work properly, or sometimes, not at all - even if it physically fits and is the right overall type (e.g. SDram, DDR, DDR2, etc.; PCxxxx, xxx mhz) for your mboard. In the worst cases of incompatibilty your mboard WILL NOT BOOT with it installed, and the mboard may not even beep - the ram has to be compatible with the mboard and it's chipset.
See response 5 in this for some info about ram compatibilty, and some places where you can find out what will work in your mboard for sure:
http://www.computing.net/hardware/w...
Correction to that:
Mushkin www.mushkin.com
Once you know which module ID strings work in your mboard, you can get them from anywhere you like that has ram with those ID strings.
In my case, only the ram module I could not find whether it was compatible or not, of three I tried, caused the problem.
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A common thing that can happen with ram, even ram that worked fine previously, is the ram has, or has developed, a poor connection in it's slot(s).
This usually happens a long time after the ram was installed, but it can happen with new ram, or after moving the computer case from one place to another, and I've had even new modules that needed to have their contacts cleaned.
See response 2 in this - try cleaning the contacts on the ram modules, and making sure the modules are properly seated:
http://www.computing.net/hardware/w...
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If you do a ram test, do that AFTER having tried cleaning the contacts and making sure the ram is seated properly - otherwise any errors found may be FALSE.
If the ram is incompatible with the chipset, it will likely FAIL a ram test - that is NOT a true indication of the ram being faulty - there is probably nothing wrong with it, and it will pass the test if installed in a mboard it is compatible with.
If you want to try a memory diagnostic utility that takes less time to run a full pass than memtest86 does, this one is pretty good - Microsoft's
Windows Memory Diagnostic:
http://oca.microsoft.com/en/windiag...
It can be toggled to do a standard or a more comprehensive set of tests - use the latter one. A few of the tests are intentionally slower.
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"i preinstalled windows on my hdd"
When you install a hard drive that already has Windows 2000 or XP on it that was set up on another computer, if the difference in hardware is more than a little different, 2000 or XP often cannot deal with the change and will not boot all the way into Windows - typically you see the first bit of Windows graphics, then a black screen with a blinking cursor top left and nothing further happens.
(However, I have have never seen or heard of this problem causing your computer to re-boot)
In that case you need to run an XP Repair Setup, often called a Repair install.
An XP Repair Setup will (almost always) not harm your existing Windows installation, but it can only fix things Windows detects as wrong, and/or replace corrupted or missing Windows files that are on your original XP CD. In the case of drastically changed hardware, it will set Windows to the new hardware situation.
You will need a Windows CD of the same version as the one of your Windows installation, and the Product Key, preferably the one that was used to install it, but it can be one for the same version as the one of your Windows installation.
How to do an XP Repair Setup, step by step:
http://www.windowsreinstall.com/win...
You will need to load all the drivers for the mboard after Setup is finished.
If your Windows CD does not have SP1 or SP2 updates included, and you updated to SP2, you may have to install SP2 again to get it working properly. SP1 or later is required for USB 2.0 and hard drives larger than 137gb (manufacturer's size; 128gb in Windows and most bioses).
You may also need to re-install your Windows Updates.
NOTE: I have found some older XP Home CD's without SP1 or SP2 updates (e.g. made in 2001 - see the date on the CD) DO NOT have the screen with Repair Setup option! See Slipstreamed CD (below) in that case - you should have the Repair Setup option after you make that.
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Slipstreamed CD
If your XP CD does not have at least SP1 updates included, and you have hard drives larger than 128gb (in Windows; = 137gb manufacturer's size), and/or USB 2.0 support on the mboard, you need to burn a slipstreamed CD that has the contents of both the original Windows CD and the SP2 updates
- e.g.
Slipstreamed Windows XP CD Using SP2
http://www.theeldergeek.com/slipstr...
Directions for using Roxio or Nero.
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Slipstream Your Way to Safer, More Secure WinXP Systems
http://www.crn.com/white-box/186700253
The elder geek site mentions you must add the Microsoft Corporation.img file to the CD - the crn site explains what it is and where to get it.
"While you've got the Windows XP installation disc in the drive, take a few moments to extract the Microsoft Corporation.img file from the disc. The Microsoft Corporation.img file is an image file, and it's a critical component for compiling the bootable Windows XP CD image"
The crn site uses freeware programs to make a slipstreamed CD.
Optionally you can also use the freeware nlite to do it, and also integrate hot fixes.
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