Question Reactivated old PC freezes after CPU upgrade?


Apr 20, 2016
I reactivated an old PC, as follows:
MOBO: MSI P965 Neo, latest BIOS version 2008, I don't see any newer ones
PSU: 400W
RAM: 8GB (max it can handle), working fine
CPU: Core2Duo E6700
GPU: something archaic
system: Win 10
cooler: Arctic Freezer 7 - should well handle the quad core as per specs

Now this was the setup working just fine. I upgraded GPU to nVidia GTX 750 Ti. Working fine. Just the DVD (Optiarc) stopped working. BIOS won't read it. Well, fine, it has an IDE cable and GPU is pushing on this cable now, maybe it got damaged. I will change that to SATA later with an adapter. Next I upgraded CPU to Core2Quad Q6700. Same thing technically as the duo, just quad. Now weird things started to happen:
  1. Bios started to read my DVD ROM...hmmm, weird, I have no explanation for that
  2. BIOS couldn't read my CPU. During the startup it said CPU-quad core in BIOS, but a message "Warning! CPU has been changed, re-enter settings in BIOS"....perhaps it also said the checksum error in earlier messages but don't remember. CPU-Z could read it is a quad, but parameters were from Duo still. And system (in win 10) says Core2Duo
  3. I have noticed the time my system reads is 3hrs less than it should be. So I corrected the time. Next I went to BIOS, looked for something to change, but haven't really found anything.
  4. After couple of restarts, the BIOS, itself stopped showing error messages. After startup, CPUZ shows it's a quad with correct parameters. I haven't changed anything in BIOS in this matter. Just some parameter from 32-bit to 64-bit as I have win10 64-bit. Also in win10 - system - it says core2quad. DVD ROM still starts correctly. That would be the end but...after 3 mins system freezes. I can do whatever I want - browse or idle, cca 3mins and screen freezes. I need a hard reset.
  5. I changed the battery on MOBO - I thought that this time issue, reading/not reading DVD ROM...that maybe the battery needs replacement. But it didn't help. 3 mins - freeze.
Now the win10 got corrupted, blue screen, I will see how I can fix that with another PC I have, I hope I can make a win10 repair tool. But any ideas what might cause the above? I had the idea to use this old PC behind my TV and use it for playing older games i.e. forza horizon 3 for kids. I connected the PC to TV, when it had a quad but BIOS understood it still as Duo - so no freeze - and GTX 750Ti hdmi-hdmi was working fine. TV shows the screen, says a message 1920x1200 resolution, 60Hz. With 4k cable it should be even better, but Full HD should be good enough.
MOBO doesn't list this CPU, but MOBO was released before the CPU, so logically my manual doesn't have it listed. Quad was released in 2007 and BIOS upgrade is as of 2008 due to "CPU suported list upgrade". I had this question on this forum 5 years ago and was advised the MOBO would handle this CPU.