Specs : Ryzen 5600 B450 Gaming Plus Max 16 DDR4 3200 RTX 2080SUPER ADATA 850W Gold Pc was working fine Woke up start the pc no image Resited the GPU PC start working So i decided to clean up the pc After cleaning and reassembling pc wont boot with CPU debug LED ON Took out the CPU from socket found some thermal past under the CPU Cleaned the past reinstalled CPU same no boot led on Installed another CPU Ryzen 3600 same no boot led on Took out CPU disassembled socket and cleaned it Reinstall Ryzen 3600 no boot CPU led off GPU led on Resited the GPU no boot tried another GPU no boot installed GPU in the second pcie finally pc boot Tried to limit pcie lanes in bios starting with 8x8 pc boot but windows froze Tried 8x4x4 pc boot. windows start normally . Did a lot testing everything works except GPU running at 8x Reinstalled Ryzen 5600 same thing only 8x4x4 works fine What do you people think : socket problem cpu problem pcie lanes bios corrupted
Somehow you either told us the story from it and to back. Or just a part of it. What are the odds that one finds TIM under the CPU on a working fine computer? Don't get me wrong, but TIM either is not electrically conductive, therefore isolate the CPU pins, either it is and favours the production of magic smoke. Chances are that there are still TIM residues in the CPU socket, or there is in the PCI-e slot. Check both with a magnifying glass. Clean both with breake cleaner (found in automobile parts store). It dissolve silicon grease like nothing. Alcohol doesn't stand a chance.
So it was functioning properly and suddenly problem started and system can only boot when gpu in pcie slot 2 and set to 8x4x4 in bios. What motherboard do you have ? Suspected faulty motherboard.