The problem I'm having first occured in December. One day my PC powered off for no reason while I was using it. I got no blue screen or anything, just an instant power loss and and odd crackling sound from within the case, but it wasn't very loud or anything so I don't know if it is relevant. Then it would not start up again unless I switched the PSU off and then back on. Even then, it only ran for a few seconds and instantly shut down again before I could even get into the BIOS screen. If I waited longer before turning it on then it would run for longer, but eventally the power would still die again. So I opened up the case to dismount and reconnect everything, and my PC ran fine for a few days afterwards. I ignored the problem, thinking it was a loose component or an electrical short somewhere, but the same thing happened after 4 days. The most logical explanation was a faulty power supply unit, especially since this one has been making loud chirping noises from start, so I sent it back to the manufacturer and received a new one. This did not fix my problem. This time, instead of the entire rig powering off, it seemed like only my graphics card was losing power supplied by the PCI-E cables, but not from the motherboard. The monitor would instantly lose signal, the fan on the card would turn to full speed and a red light would come on. I installed the new PSU 5 days ago and this happened 3 times so far. On the 4th time, just yesterday evening, my PC just shut down altogether like it did before the PSU replacement. It still wouldn't turn on again unless I switched the PSU off and then on again, but this time it stayed on. Originally I got this PC from CyberPower about 2 years ago, but since then I disassembled everything and moved it to a new case, upgraded the cooling and the PSU, so I doubt that any warranty I might still have from them has not been voided. It will probably come down to hiring a technician to take a look at it, but before that I was hoping there might be someone on this forum that might have some insight into this problem, maybe having dealt with something similar in the past. September of last year was when I switched computer cases and put the new (now replaced) PSU and CPU liquid cooler in. But there's no chance the problem was caused by a new case or cooler, and like I said I already replaced the PSU. Here are some facts: - When my PC does run, it runs great. There are no slowdowns, no error messages, and no signs of anything whatsoever being out of order. - All temperatures are well withing safe ranges at all times. At least they are according to EasyTune6 and Catalyst Control Center, if they can be trusted. - When turning the PC back on afterwards, I only get the black "windows has shut down unexpectedly so pick if you want to start it normally or initiate system repair" screen, if even that. - There are absolutely no burn marks or scratches on the motherboard or the smell of burnt component within the case. Still, I think the problem is either the motherboard or the graphics card. - The system will power off whether it's under stress or not. It happened to me while just browsing the internet and it happened to me while gaming. My system is: MoBo - Gigabyte GA-870A-UD3 CPU - AMD Phenom II X6 1090T RAM - Kingston 2GB DDR III SDRAM (2 sticks) HD - SATA III 1 TB PSU - Was Corsair TX950W before replacement, they kindly replaced it for the HX1000W. I'm finding it hard to believe the problem is caused by a component going bad for no reason in a relatively new system. Maybe the issue lies in the software? Maybe something is causing Windows to instantly shut down without prompting, but then that wouldn't explain how the system stays on but the GPU loses power.