1. This one could be a PSU issue since the GPU is known to pull a lot of power.
Supply a link to the PSU's maker's web page for me to check specs.
If you do this work yourself you want to not only exceed the Watts but the +12V RAIL shall be a single. No dual, triple or quad rails for the +12V for this one.
2. The BIOS is quite old. Check for updates.
3. The RAM is mixed. Always a fine source of random issues. Pull out the 2x4GB until the machine goes stable.
reboots when I play some games it doesn't seem to be a heat problem my temp stays below 70 while playing sometimes it can reach 75. not sure how to troubleshoot but ive been searching for a few days. I purchased this pc about a week ago but I had knowledge of the problem and im trying to fix it. please help.