Question Computer Won't Post

[philosofool]

TL;DR: My old computer which was working this morning suddenly won't post after I tried to add an SSD.

I have a very old computer (1st Gen Core i5) that was working fine this morning. But it was running on a HDD and I have an old SSD that I wanted to put in to speed it up. I shut down the computer, disconnected the SATA cable from the HDD, connected it and power to the SSD, a USB with Ubuntu and turned the machine back on.

Hard fail. It didn't post. Spins the fans, Mobo lights come on. Turns off. Turns back on and repeats until I turn off the power.

This is a 1st Gen Core i5 750 on a P55-UD2 Motherboard from Gigabyte. It was my Ubuntu/Development machine.

I removed one component at a time, disconnecting them from the PSU and unplugging any cables to the board. Stripped down to a single stick of RAM and the CPU, it still does not post. I reset the CMOS. No dice.

This basically leaves three possibilities: the motherboard, the RAM, the CPU and the PSU. Am I missing anything? Did my beloved old machine die? I have a PSU on my better machine (why I don't I just use the better machine? TL;DR: COVID) which I will try out later, but if there's another thing to consider, let me know.

 

[Steltek]

Is the CPU fan spinning when you start the machine up?

Were it me, I'd definitely try changing the PSU. The machine is old enough that the PSU may have just died when you shut it down to swap the drives.

 

[VirtualLarry]

Yeah, sometimes, PCs that old suffer a sort of "immenent death", should they ever be turned off.

Btw, consider replacing the CMOS battery. Unplug PC, remove battery, wait a 60 seconds, then install battery, then re-connect power. Install CPU, RAM, and if need be, a lower-end GPU. Then see if it POSTs.