Okay so I have this issue with a jailbroken PS3 fat model CECHK01 running EvilNat 4.89. This is NOT just a overheating issue (and likely isn't a overheating issue at all). So I have been repairing these systems for over a year now and I have learned a lot in the process. I have performed multiple successful delidding procedures (over 100 at this point by crafting my own tools), reflowing, reballing, testing capacitors, replacing NEC Tokins, case modding etc. The system can be off for days at a time, you press the power button, system starts to boot for about 1 second then cuts off, three beeps, then flashes red light. Interesting aspect is that for me if I hit the power button again to stop the red flashing light and immediately hit the power button again, the system boots up just fine and continues running for however long I want it to run. Temperatures are well under control with this system. CPU and GPU temperatures hold together in close proximity of 55 degrees Celsius and 56 degrees Celsius respectively with 33% fan utilization running the Last of Us for over 45 minutes in the downtown scene (one of the heaviest load scenes by any game on the PS3). I have even gone as far as replacing the entire motherboard and blu-ray drive, logic board, ribbon cables, and wifi board (so basically a whole new system). The only thing that has remained consistent is the power supply unit. As you can tell I am performing a process of component elimination to narrow down the exact problem. I am moving on to the PSU next. I saw an interesting video of an engineer disassembling the power supply unit and using a flat head screw driver to adjust the capacitors/transistors (I believe I can't remember the exact nomenclature) by tuning them and changing their direction by about 1/4 of a turn or 90 degrees and that seemed to resolve the entire issue. I truly do not believe this is an overheating issue and everyone seems to want to jump to that conclusion for some reason and then they recommend potentially damaging procedures such as delidding, attempted reflowing, reballing, NEC Tokin replacement, etc. Now I will say this, from my experience if you have been playing the system for 15-20 minutes or longer and the system shuts down and flashes the red light, then yes, most likely that is a overheating issue and you need to verify your CPU/GPU temperatures. However, if the system has been off for over an hour and you try turning it on and it immediately does the triple beep and flashing red light I believe it has something to do with the startup process and possibly a failure of the PSU to deliver adequate power initially to start the CPU, hard drive and blu-ray drive all in one go. If anyone else has any other ideas or fixes I would be overjoyed to learn about them and receive the professional feedback/criticism in order to enhance my own learning. Hopefully this will give you an idea of where to head next and save you and others some time, money, and frustration.