EDIT: I might not have posted this in the correct forum section. If so, maybe a MOD would be so kind to move it to the correct section? I have a weird problem with my computer that didn't seem to get solved by changing the motherboard, cpu and memory. It's going to be a long story, so please bare with me. Let me first give you my system specs. My old setup: CPU: I7 4770K @ 4 GHZ Memory: G-Skill Ripjaws 4 x 4 GB (DDR 3, 2133mhz) Motherboard: Gigabyte Z97x gaming 3 GPU: MSI RX VEGA 64 (undervolted and cooled by alphacool's eiswolf) PSU: Corsair RM 1000 Storage: Samsung 840 EVO (256GB) + 850 EVO (512 GB) This is my current setup: CPU: I7 8700K (was overclocked at 4.9 ghz) + Noctua NH D-15 Memory: Corsair Vengeance LPX 2 x 8GB (DDR 4, 3200 mhz) Motherboard: Gigabyte Z390 Aorus PRO GPU: MSI RX VEGA 64 (undervolted and cooled by alphacool's eiswolf) PSU: Corsair RM 1000 Storage: Samsung 840 EVO (256GB) + 850 EVO (512 GB) Let me start at the beginning. This week I was playing Assassins Creed Odyssey and all the sudden my PC locked up. After I pressed the reset button, my PC wouldn't POST. It powered on, but nothing happened. I had to hold the power button for a couple of seconds to shut the computer down. After a couple tries, the PC booted up again and I started playing ACO again. After 20 minutes my PC locked up again. The same problem as before occured. My PC powered on, but didn't post. I connected the speaker to the motherboard to check for beeps, but it didn't peep. However, the speaker made a clicking noise every few seconds (maybe it wanted to beep, but was cut off because the pc restarted?). I managed to boot into windows again and I decided to lower my overclock (maybe it became unstable after 4,5 years of use). I played ACO again and didn't have any crashes. I shut down my computer at the end of the day and went to bed. The next morning I tried to boot my PC, but it wouldn't posted. It took me a while to get it working again, by removing some ram stick. However, as soon as I shut down the PC completely and did a cold boot the problem occured again. The only way to get the computer started again, was by either removing a memory stick or place one back in. The computer didn't have any problems with a warm boot, only a cold boot caused problems. Next thing I did was removing the GPU and run my PC on the intel graphics. This didn't solve my problem. I still needed to remove or add a memory stick. I was so frustrated, that I ordered a new cpu, motherboard and memory (I needed an excuse to upgrade anyway). After I ordered everything, it hit me. Why not try to flash the BIOS? This seemed to do the trick. I didn't have to swap memory stick around anymore. ------ As soon as I got me new hardware, I was trying to overclock it. I did run Prime95 for over an hour and it didn't show any errors (Im aware that you need to run it alot longer to see if the CPU is 100% stable). I could also play ACO just fine. Yesterday my PC started to lock up again twice. So I dailed back the overclock a little. The game was running fine again. Today however, while playing ACO my PC locked up twice again after 30 minutes. After this I decided to run my CPU at stock settings and I could play the game for over 2 hours. This evening I decided to play Black Ops 4. I played two matches and my PC froze again. I pushed the restart button and then I heard 5 short beeps. According to Gigabyte this means a CPU error. Pressing the restart button gave me 5 short beeps again. After holding down the power button for a couple of seconds, my PC booted again. I don't know what is happening here. Since I swapped out most of my hardware, I would assume that either my GPU or my PSU is faulty. However, I can run GPU and CPU stress tests without any problems. I can even combine a GPU and CPU stress test. My temperatures are fine, nothing is overheating. I monitered all the sensor with HWinfo64 and nothing unusual pops up. It's just games that seem to be unstable. I know it's hard to determine what the problem exactly is, but can anyone give me some advice/help with this problem. I'm getting really frustrated here, because my week of is totally ruined by this problem. UPDATE: I look in the event log and the display driver crasht right before the computer freeze. With my old setup, the display driver also crash twice this week during a youtube video. Could still be the PSU.