Boot issues / PC won't boot

So, I don't even know where to start—just spent way too much time scrolling through forums looking for a fix. I can build and tear down a PC with my eyes closed, so I’m turning to you guys for some actual help.

Basically, about four days ago, I decided to strip down my Cooler Master NR600 just to give it a good cleaning, nothing unusual. Everything seemed fine until I put it all back together and tried to boot. Now, it’s like the motherboard is dead—zero signs of life. The fan LEDs kick on, sure, but the monitor, mouse, and keyboard are completely unresponsive. At first, I figured I just missed a connection somewhere, so I shut it down and double-checked everything. It looked solid. Then I tried the old "magic fix"—reseating every single component—but nope, still nothing. Tried clearing the CMOS thinking that might jumpstart things, but another disappointment. I even tried booting with just one 2GB RAM stick, then swapped it for the other identical one... nothing. I even reseated the CPU, which shouldn't have been necessary since it was working fine before the cleaning, but hey, desperation is a hell of a thing. Since I have no clue which part is bricking the whole system, I'm stuck. I've pretty much ruled out the monitor and the RAM. I'm also leaning away from blaming the PSU, since it's relatively new and hasn't given me grief until now.

Setup:
Intel Core i5
Intel B85
Corsair Vengeance 4gb 1600
Geforce GTX 460
Corsair CX600
Western Digital 500gb hard drive

I'm at a total loss here, so give it your best shot.🙂

From what I can tell, it sounds like your motherboard might have finally kicked the bucket. If you can manage it, it’d be worth trying to grab another board with the same socket—just to pop your current processor in there and see if the PC actually boots up with a different board... Or, honestly, maybe just try swapping out the CMOS battery first? Might be worth a shot...

Larry Ortiz5 said:From what I've seen, looks like the motherboard finally kicked the bucket. If you can, try grabbing another board with the same socket—pop your current CPU in there and see if the rig actually boots up. Might also be worth swapping out the CMOS battery just to rule it out...

My first thought was just to grab a new motherboard—didn't even think about testing it like that.
Thanks for the tip 👍