1. Driver updaters are not called for. Get your drivers from the makers and done. Said updaters AUTOMATICALLY BREAK PC SETUPS. Great stuff to create work for repair shops.
2. PSU Watts. Sorry no. I look at the PSU as to it's ratings on the rails. The thing is this is many years old so a 600 Watt PSU can lose capacity over the years. The test at the shop breaks down to:
a. Use the P3 Power Meter to measure the total power draw of the computer.
b. At years old, use 50% of the PSU rated capacity, if newer at 1 year, use 75%.
c. If the power draw maximum is over or close to the 50% then you may have a power issue. Swap in a new PSU with 100 more Watt capacity and SINGLE RAIL +12V.

3. It can be a graphics card as we've seen one game work, another fail and you swap cards and both work. Expensive to diagnose as you need a spare card of the same make and model. Shops will just use what they have.

4. Small world. My son's PC had the GTX 970. It failed recently.

LET'S BE CLEAR HERE. If you expect anyone to tell you "it's this" then expect to be disappointed. But if you are ready to try again, run the PC through the usual steps to see if you can avoid new hardware.

1. Current BIOS. Reset and change the bare minimum to bring the PC up.
2. NO overclocking.
3. Drivers per the makers. Do not use driver finders.
4. Clean the PC with the usual canned air. Consider heatsink compound for the GPU as well. That varies with the skill of the owner or tech.
5. PSU. Until you get a true measure of power use, it's suspect. No I did not write it is this. If the PSU is a multi-rail +12V, it's even more suspect. Stick to single rail +12V models.

6. Supply the forum with the exact PSU model or a photo of the specs on the side of the PSU.
7. Supply the forum with a SPECCY and USERBENCHMARK.COM report.
Example: https://www.piriform.com/docs/speccy/using-speccy/publishing-a-speccy-profile-to-the-web