Built a computer and it shuts itself down - not heat, not PSU
Solution 1:
In this case, I would follow some basic troubleshooting guidelines.
Step 1) Determine a reproducible process for testing the issue. You need a set of steps to take that will make the system crash each time you do it. The best process is one where you can walk away and do something else while it is running. the best processes don't require anything more than windows, but that can sometimes be a challenge. You will be doing this process constantly until you determine what it wrong. Before you move on, make sure that you can perform the test on a known working machine. You don't want your test to crash all computers, just the one having problems.
Step 2) Reduce the number of variables down to the smallest set. This is where you start removing hardware until you have a bare bones system. You can start with reducing down to 1 stick of ram, removing extra peripherals, and disconnecting hard drives. This is also a good time to reduce the number of running programs down to the fewest possible.
Step 3) Eliminate the OS/Programs from consideration. Get a known good blank hard drive and reinstall windows onto it. Add the latest manufacture drivers and any software needed to test for your error.
Step 4) Start swapping components with known good ones. This is the most time intensive and difficult step to complete. Find compatible hardware and start changing things out. I'd go in this order:
- Video Card (sometimes good to go with a different chip-set series)
- Memory
- CPU
- Motherboard
- Power supply
- Case
If you can't figure out what is wrong after doing all of the above, then you may just need to trash the whole system and build a new one from scratch. What you currently have should work together as long everything is configured correctly.
Hope this helps
Solution 2:
One possibility is a short-circuit between the motherboard and the case. Check the clearance between the motherboard and ensure that there are no contact points between the motherboard and the case except for the mounting points. You might try getting some spacers to raise it slightly higher just as a test.
Another possibility (though a slight one) might be a "brown out". If the circuit the computer is running off of doesn't supply enough power for the computer, resulting in an under-power condition, it can cause the PSU to shut off because it is not getting enough power to run the computer.