Sorry to hear that! You don’t need to read all of this, but your troubles might be somewhere around items 4 or 5. Tl;dr some common troubleshooting feedback loop tips from my experience.

Not that this necessarily applies to you, but in case anyone else comes across this thread. As with any repair, start simple and eliminate possible causes one by one. I cannot stress enough how important it is to make 1 change at a time when troubleshooting— it can be tempting to open the computer and try to make all possible changes at once, but you’ll only create new problems down the line, and won’t be able to eliminate old problems.

My usual diagnosis order of operations is something like this, though by no means is this extensive:

1. Determine if it’s hardware or software related— a good rule of thumb is if the computer is hard-crashing, i.e completely frozen, unresponsive, or power cycling— it’s probably hardware. If the program is crashing but you can still get back to desktop, get error codes etc. it’s possibly software. Since software tend to be more easily google-able, the rest of the list is for hardware. Issues with the operating system are also pretty annoying, but a fresh install of your OS is usually a safe way to fix most of those problems.

2. Check that all the connectors are properly seated— the number of times that “my computer won’t work!” Is solved by plugging it back in…. It’s astonishing. Internal and external connections— people often forget to turn the PSU on, or to plug the video connector into the GPU instead of Mobo, or forget to plug a sata power cable into a drive, etc.

3. Boot into bios, use whatever tools your bios has to check your hardware and make sure everything looks right— temps, memory timing, remove any overclocking, check boot config etc. kinda dependent on whatever issue you think you’re facing. If you can’t even get into OS and/or BIOS, Remove your ram sticks, then put one stick into the 1st slot, repeat bios investigation, boot back into OS. If that doesn’t work, reset CMOS per Mobo spec.

3a. If you can get into BIOS but not into OS, it’s probably a boot config issue— check that your boot drive is showing up, disable (or disconnect) all other boot options and force it to use your selected boot drive. If it’s not booting, swap the cables and see if that works, otherwise prepare a new boot drive if you can. Presumably you want to recover your data from your boot drive because most of us don’t have to foresight to keep our data off our boot drives… so get a second drive to create a new boot drive, and see if you can access your original drive’s data once you get back into OS.

3b. If you can’t get into BIOS at all, your hardware is not installed properly. Go back and fix all connections, reseat your CPU and remove everything that is non-essential. But if that doesn’t work your CPU or Mobo is likely damaged beyond repair.

1. Hardware DOES fail, but in my experience it’s usually power or cooling related. Getting a high quality PSU is a MUST, but unfortunately that’s where most pre-builds and first-time builders cut costs. It’s not worth it. It runs the risk of damaging your whole build, causing a fire, blah blah blah. The peace of mind is worth the few extra dollars for a high quality PSU. And get one with a good amount of headroom! If your system needs 500w, put at least 650w+ PSU in there

4a. If your computer is randomly crashing/restarting/powering off during “standard” actions like web browsing, productivity, etc. (NOT more intense stuff like gaming), there’s a good chance your power supply is on its last legs.

4b. If you’re crashing when you launch a game, it could be PSU (pc is now trying to draw more power that PSU cannot provide, triggers a shutdown to protect itself) or it could be cooling (CPU is quickly getting too hot as workload increases, triggers shutdown). This is where I have often ended up, But it’s been a 50/50 split between failing power supply and failing cooler. If you have a water cooler, there’s a good chance that’s the culprit. There’s just more moving parts and points of failure. Try switching to an air cooler and see if that helps. If air cooling doesn’t do the trick, swap the PSU.

1. If your cpu came with a stock cooler and it fits in your case, definitely try using that stock cooler, or another small simple air cooler (they’re cheap and good to have on hand as a backup). Sometimes the fancier coolers like AIOs or big heavy air coolers require additional parts like brackets etc. and each part adds in a point of failure.

5a. If you use decent thermal paste and apply it correctly, it should last you a good while, a few years maybe. Anytime you take your CPU cooler off, though, you should clean and reapply thermal paste. Thermal paste can go bad in the tube, becoming dry and flaky or having liquid kinda separate from the paste.

5b. Depending on your cooler and cpu, there may be a bracket or mounting hardware that is actually preventing your cooler from making proper contact with the CPU. I swapped coolers and didn’t realize that the mounting bracket on the two coolers had a millimeter difference in the standoff screws. Thus, even with the screw fully tightened, and the cooler appearing to make good contact with the cpu/thermal paste, it actually wasn’t transferring heat efficiently. This can be really difficult to diagnose if you aren’t looking for it.

Anyway, enough ranting! Good luck!