PC freeze odd problem

Hi all,

I have pretty odd issues with my PC, I got this second hand custom build for a bargain and I have some issues I can't resolve by myself. At first, everything was fine than some problems came up. I was well aware of the risk I was taking. I have read pages and pages and tried many things but no luck.
Now, to the problem:
PC freezes randomly in all occasions, weather browsing the internet, playing videos or using some software, playing games...Sometimes after exiting some games I get black screen and need to hard reset PC. When hitting say ctr+alt+del PC hangs for few seconds. Other symptom is mouse pointer gets distorted, enlarged and colored, sometimes it disappears or becomes thin yellow line etc. I found on this forum temporal fix, to enable mouse trails, it solves desktop/YT videos lock up but random hangs continues as mentioned above with programs and exiting games.
Freeze lasts for a few seconds than everything is ok than again, restart helps but after some time problem comes back it can be an hour or a day with no order, it appears with random tasks. Problem does not occur in safe mode. When I monitored systems nothing spikes, it just pauses.

What have I done so far:

1. Reinstalled GPU drivers, rolled back GPU drivers to known stable ones, nothing.
2. Reinstalled mouse drivers (even uninstalled drivers and let windows to install native ones)
3. Reinstalled win7 with formating and installing on other HD to rule out HD issue
4. Scanned with several antivirus like Avast, AVG, Bitdefender and several antimalware like Malwarebyts, Adaware, Spybot, done that in safe mode too, only 1 issue found and quarantined
5. Changed mouse (USB)
6. Monitored temperatures on CPU, GPU and HD all checks out fine
7. Cleaned ventilators and RAM sticks, checked cables
8. Installed driver updates
9. Ran win memtest, chdsk, sfc, nothing
10. Defragmented
11. Underclocked GPU
12. Did system restore
13. Installed all windows updates
14. Increased/disabled paging file
15. Stopped/enabled various windows services
16. Disabled/enabled antivirus, windows defender, windows firewall, tried all combos

I tried the most fixes there is

What I didn't do is BIOS update because of another problem I have and that is PC won't restart properly.
After pressing restart I can hear booting up but no display. I have to power off and wait for a minute or so and it boots up normal.
Few things may help pin pointing problems:
I use DVI to VGA adapter
PSU is 375W
CMOS battery is maybe dying
Didn't tried to test RAM sticks - that is next thing I'll do

Please help

Welcome to the forums IgorNS!

You could try a repair install.

Repair Install

Could be a hardware problem though.

If changing resolutions solves the problem, the issue could be your graphics card. That's a pretty old card. It might be starting to fail.

The monitor is not likely the cause of the freeze. It's probably the graphics card causing the problem. That would be my guess, anyway.