I am having the weirdest issue with a Dell T3600 I cannot figure out, and any help is appreciated. I know this is going to be long, and I appreciate the time anyone takes to read this and help me. I am going to walk you through all of the steps I have taken thus far and what is temporarily working to fix the problem.
Problem: The computer started to randomly shut down overnight. When I would try and turn on the computer at the start of the day by pressing the front power button, all of the fans would come on full blast and just continue running for several minutes at full speed, but the displays would not come on and the computer would not boot or do anything. I would then pull the power cable from the back of the computer, wait a few seconds and plug it back in. (Sometimes having to repeat this step several times) and the computer would eventually come back on and give me a warning saying the computer shutdown because it overheated. A few weeks ago I upgraded the bios and shortly after the machine stopped turning on completely.
When the computer will not turn on, it goes into a state where either all of the fans kick on full blast (CPU fan, 3 front panel fans, GPU fan, and power supply fan) and will not stop till the power cable is removed. Or the second state is the front panel power light is very dim but illuminated, and an amber 3 and 4 are present. Pressing the power button toggles between the Power button going completely dark or slightly illuminated, but the computer never boots. When the power button is slightly illuminated the GPU and CPU fans are running at normal speed.
Attempts to resolve the issue: I want to preface this by saying that we have another t3600 that has been working perfectly this entire time, so I will reference using parts from this T3600, that works perfectly during this. In all of my attempts I am using the same graphics card, hard drives, and RAM chips that are working in one machine, and not on the other, so it is certainly not these that are the problem.
Replaced the CPU chip from one bought online - Computer acted the exact same.
Replaced the motherboard with one bought online- Computer acted the exact same.
Replaced the motherboard/CPU with a SECOND separate set bought online - Computer acted the exact same.
Tried every combination of RAM chips. Tried one chip at a time in each of the 4 slots. Also tried with the 4 working RAM chips from the other T3600 that works, as well as a spare set of RAM chips (that also work in machine 2). - Computer acted the exact same with every possible combination of RAM chips.
Pulled the CMOS battery to reset the CMOS - Computer acted the exact same.
Swapped power supplies between the working and none working T3600. The working machine works with both power supplies, and the broken one acts the exact same with both power supplies.
Thought it might be the physical front panel of the machine and the power button wasn't working. Swapped the front panel chip with 4 USB's and audio jacks, but left the wiring in place. - Computer acted the exact same.
It was at this point I was about to take this computer out back and just go full office space on it when I tried one last thing. I just unplugged all of the front panel fans and the long plug (3 wires that go to this one plug) that connects the USB ports as well as the power button from the motherboard. (I left the audio plug and the solo USB thick cable plugged into the motherboard) THE COMPUTER TURNED ON!!!! I got warnings about the fans not being plugged in, but pressed f1 and the computer started up like normal. After several series of attempts I have narrowed it down to the actual CABLING/PLUG from the front panel to the CPU. If this cable is plugged into the motherboard, the computer will not boot and fans kick on, if it is unplugged, the computer boots and acts perfectly normal. So we ordered another front panel/cabling. It came in today and I was excited to get my front panel USB's back. Replaced the entire front panel (again) but this time I replaced the cabling as well, and the computer is doing the same thing as before, where it won't turn on or the fans are running full speed!!!!!
I am at a complete loss now. I have been using the computer for 2 weeks with the 3 wire plug unplugged from the motherboard and it has been working fine, but I have to unplug the power from the back of the machine and plug it back in to turn the computer back on after it has been shut off. I also do not have access to the front USB ports.
WHAT IN THE WORLD could the problem be that is causing this issue, and how can i fix it. THANK YOU in advance!
EDIT: One other thing I noticed yesterday. If i put the computer to sleep, instead of turning it completely off, as soon as it goes to sleep all of the fans kick on full blast and start running till I pull the power cable from the machine. When I say full blast, I mean like people down the hallway can hear them and ask if that was my computer. This is repeatable. If i simply shut down the computer. It shuts down without any issues.