[SOLVED] Suspect CPU was damaged during CPU Cooler replacement?

[Athelath]

Build info here: https://pcpartpicker.com/list/mXGpcq

My CPU shot up to 98c a couple weeks ago, so after shutting down and doing some research, I found out my initial liquid cooling choice was not a good one (NZXT Kraken M22 Liquid CPU Cooler) Please note, I live in FL.

I initially attempted to replace the thermal paste, which brought the temp down to around 58c. Computer was running well. But figured I'd might as well replace the CPU cooler anyway. Purchased a Noctua NH-U12S, and switched them out. But now my computer doesn't turn on at all. The LEDs on the motherboard will light up for about 5 seconds, but that's all. No fans, no nothing. Checked with a friend who builds PCs, he recommended breaking down the rig, then testing just the basic components and using a screwdriver to "jump" the power pins (I decided to use the initial CPU cooler, since I know that one works for sure). Nothing works.

Although I'm not quite sure whether its the CPU or the motherboard that got damaged, I'm leaning towards replacing the CPU first (slightly cheaper way to narrow down the issue). I took some very detailed pictures of the motherboard and CPU to look for any signs of damage or scorching, neither of us could see anything problematic.

Looking for any general advice on my game plan. Is replacing the CPU the the smart way to go, or is there any further testing I can do with the resources at hand? If I do need to replace the CPU, is it worth sticking with the i5, or going with something newer ($250 would be my limit, most likely)? This was originally a recommended mid-range gaming build from a PC Gamer article, and I've been fairly happy with it.

 

[Phaaze88]

You said NH-U12S, but your partpicker list has NH-D15... which is it?

I initially attempted to replace the thermal paste, which brought the temp down to around 58c. Computer was running well. But figured I'd might as well replace the CPU cooler anyway. Purchased a Noctua NH-U12S, and switched them out. But now my computer doesn't turn on at all. The LEDs on the motherboard will light up for about 5 seconds, but that's all. No fans, no nothing.

Something occurred after the underlined portion that you either didn't do, or shouldn't have done. You need to backtrack your steps to right before you got around to uninstalling the previous cooler.
We're not there in person to actually see what could've occurred, so the more info you can provide, the better.
With what's been provided so far, I think the cpu is fine, but assume a bad cooler install, a loose psu connector, loose fan connector, or even mis-installed a fan header(I've done that).

This was originally a recommended mid-range gaming build from a PC Gamer article

Wow, that's bad. Shame on PC Gamer.
What's bad is the combination of parts, not the parts themselves.

 

[Athelath]

You said NH-U12S, but your partpicker list has NH-D15... which is it?


Something occurred after the underlined portion that you either didn't do, or shouldn't have done. You need to backtrack your steps to right before you got around to uninstalling the previous cooler.
We're not there in person to actually see what could've occurred, so the more info you can provide, the better.
With what's been provided so far, I think the cpu is fine, but assume a bad cooler install, a loose psu connector, loose fan connector, or even mis-installed a fan header(I've done that).


Wow, that's bad. Shame on PC Gamer.
What's bad is the combination of parts, not the parts themselves.

It is the NH-U12S. I've attempted to reseat all the cables, I even went back to the original cpu cooler, since I'd previously removed it to apply new thermal paste. At present, the rig is completely dismantled and my last test was just the motherboard, cpu, m22 cpu cooler, a ram stick, and the power supply. It's quite possible I've made a mistake during the rebuild, but at this point, it's been pulled into various states of repair over four time, and it's not responding. Which makes me think the cpu was possible damaged when I tried to put on the new cooler. It's also possible that the thermoconductive paste (arctic 5) I used to replace the original stuff may have gotten into the wrong spot, and damaged something I can't see.

What else is wrong with the combination of parts? I went through pcpartpicker and checked compatibility, but this was my first build.

 

[Athelath]

Updated the list. I upgraded the RAM not long ago, and the original list didn't have the fans. https://pcpartpicker.com/list/q9XKrV

 

[Phaaze88]

If you never took the cpu out, then it should be fine - but you can screw up a cooler install by placing too much focus on one side/corner, causing uneven spread of thermal paste.

AS 5, huh?
Whoa, there's been quite the arguments over whether that stuff is conductive or not...
"Arctic Silver 5 was formulated to conduct heat, not electricity.
(While much safer than electrically conductive silver and copper greases, Arctic Silver 5 should be kept away from electrical traces, pins, and leads. While it is not electrically conductive, the compound is very slightly capacitive and could potentially cause problems if it bridges two close-proximity electrical paths.)"
So unless you got careless with it, it shouldn't have done anything.

What else is wrong with the combination of parts? I went through pcpartpicker and checked compatibility, but this was my first build.

Nothing wrong with the parts or the compatibility. Looking at your build BEFORE the M22 was replaced:
-a locked 8th gen in a Z390? Huge money sink for no realistic gain.
-a Kraken M22 on an i5-8400? Yet another large money sink, when you could've gotten an air cooler for half the price or more on a trusty Hyper 212 or something similar.
-you paid a nice little premium for that RGB ram, and the frequency doesn't benefit the i5-8400 all that much either...
-pricey Samsung SSD for what looks to be your OS drive.
-850w Corsair RMX on a build that can't even pull 400w; more premium spending here.
You overspent in a number of areas. You actually could've gotten something even better than what you currently have with all the areas you overspent in.

 

[Athelath]

The ram was given to me for free from a co-worker who was upgrading his own rig. The liquid cooler was my choice, since I wanted something quiet. But I've learned after the fact that air coolers are preferable.

Some of the others were recommendations from the article, although I don't think I could find it now. It's not a huge deal to me that some are overpowered for the current build, because I'd assumed I would be upgrading some of the hardware over time. Your feedback is appreciated though, thank you.