Hey guys, I've been trying to format two PCs from my dad's office. The PCs are identical in hardware. But they've been giving me troubles, quite a lot actually.

When I start the Windows 7 installation, they just keep restarting while Windows is installing. Same thing happens with Vista too.

Luckily, if I succeed in passing through the installation, they randomly restart while using Windows, every few dozen minutes.

I had this problem the previous time, and was able to fix it by cloning the hard drives, but this doesn't work anymore, as now both PCs are screwing up with me (the last time only one of the PC was having this problem).

I'm currently testing the RAM through Memtest86+, no errors so far. Also tried changing the optical drive, the restarts still happen while installing Windows.

Any ideas what else might be the problem?

Bad CMOS battery on the mobo?

If it's not RAM it's most likely this. Thought the fact it's happening on both is somewhat fishy.

If it was just one I'd suggest checking the PSU if its getting overloaded or dying, but with two computers that's probably not the culprit... strange. Sorry, not very helpful.

Any way to test it?

I had something same years ago.. but it turned out that my processor was overheating and it crashed in install. Don't remember if the cooler turned at all. =) but that was about then there was 98 also. well xp was released.. But it was the processor heating.

CPU / GPU / PSU coolers are all spinning, and I cleaned them up yesterday. Also the case is opened on both sides, so overheating is very unluckily (the PC of which I'm currently testing the RAM has been up for a full hour now (no restarts while it OS-less)).

Can't you boot into the BIOS itself?

Check the BIOS logs or go into the BIOS and turn off any "fast boot" options (run a full POST). If the battery is bad, it will show up in the logs or in the POST output.

Yes, I can. Will do, once a few more tests / passes of the RAM are done.

Thank you all so far!

Some systems required a BIOS firmware update in order to run Windows 7. I believe this was specifically required for 64 bit systems that were running a 32 bit OS.

Go to the manufacturers website, find the updates for the computer model and see if any Win 7 BIOS updates are available, if so, download and install.

Just in case check with a multimeter if the electrical parameters on the wall socket are alright (230V 50Hz).
Then take into consideration that the power supplies of both computers may have aged and not performing well. Better test with another PSU if you have one at hand.
Get a new bios battery, replace it in one of the computers and see if that helps. Usually these batteries are cheap so it is not a big loss.
Check if the heat sinks on the CPUs are properly seated and if the thermal paste is not dried.
In the end if nothing works remove the RAM banks one by one and see what happens. You may try different combinations of ram between the two computers and even better if you can borrow from somewhere a test memory.
Also check if the capacitors on the main board are not swelling.

Done with testing the RAM, no errors showed up.

BIOS reports that the temperature is just fine, ~40 degrees on the CPU, and ~3x on the motherboard.

What's the hardware?