Question Replaced CPU fan, now PC won't POST

Feb 15, 2020
I built my PC 10 years ago and it's still great for my needs and I've had zero hardware issues until two days ago. The salient details:
Gigabyte GA-X58A-UDR rev. 2
Cooler Master V8
12 GB G.Skill 1366
Cooler Master HAF 932 case

The story thus far:
I left the machine running but idle in my home office around 5pm and next morning around 5am went back in to start my day. Thankfully the PC in question isn't my work PC. As I got near my office I could hear what at first sounded like a continuous tone from the mobo. Not good. However, once in the office I could tell it wasn't the mobo I was hearing, and the screen woke right up and Windows looked fine. From a standing position the sound seemed to be coming from the rear of the computer, so I got down and put my head near where I thought it was emanating from, which on my quick listen seemed like maybe the PSU fan. I quickly shut down Windows.

After I finished work for the day I fired up the PC again to start troubleshooting. The sound was still there but this time was intermittent. I hadn't opened the case yet, but using a flashlight shining through the top vents I could see that the fan in my Cooler Master V8 was seizing, then running for a couple seconds, then seizing again. I immediately powered off the machine. So what I'd heard in the morning was a seized CPU fan (again, Windows looked stable under idle load). I unhooked everything, opened the case, and first gave everything a good cleaning. I try to do that 2x a year but was overdue this time.

Next I removed the fan from the V8 (thanks, YouTube), cleaned it up and cleaned the insides of the V8 fins as best as I could, and reinstalled the fan.

I hooked the PC back up and started it up, and immediately started getting long beeps. I immediately powered off. I thought, "I'll bet I forgot to plug the fan back into the CPU fan header." Yep. Unhooked everything, plugged the fan in, reconnected everything, and powered on again. This time no sound from the motherboard, no POST, and the CPU fan didn't budge. So apparently I finished killing it by cleaning it. It's not like I would trust it again anyway.

I ordered a new Cooler Master Sickle Flow 120 fan, which was the consensus best replacement fan from the reading I did, since it's basically the same fan as the original V8 fan minus the speed control dial. The fan arrived this afternoon, and I immediately swapped in the new fan for the old.

The only difference between the fans (other than the speed control dial) is that the new fan is a 3-pin, whereas the old fan was a 4-pin. I assume this is not an issue since the 4-pin header matches the notch on the 3-pin connector, and that the unused 4th pin is for speed control.

Hooked the PC back up, powered it on, moment of truth -- and as you already know from the post title, the machine won't POST. But the new fan glows red and is running great, so there's that.

Next I unhooked everything and tried clearing the CMOS via the button on the back of the computer. Held the button in for a solid minute. No change. So I unhooked everything, popped out the CMOS battery for an hour, put that back in, no change.

That brings us up to the present. The CPU fan runs and all 4 case fans run.

The phase LEDs are green, green, yellow, yellow, red, red. This is how they've always been. The DDR phase LEDs are green, yellow, green, yellow. Again, I'm pretty sure that's normal.

At this point I'm thinking that I must've fried the CPU. Although, again, I saw no signs of instability when I initially discovered the problem, and after that I only ran the computer once where it POSTed and I shut it down within 30 seconds of powering it on.

Ambient temp in my office at night is about 68 degrees. The V8 cools really well and in addition to the CPU fan the HAF 932 has big fans on 3 sides of the heatsink. But maybe the circumstances were enough to do the damage.

Before I start in on swapping the CPU, is there anything else I should try?

And if I do need to to replace the CPU, any recommendations on an upgrade from the i7-950? It's been a great CPU but since it's a decade later if there are other better options I should consider, I'm listening.

Thanks much.