I'll try to keep this detailed and concise. I have no idea what I could've done to cause this. Just a week ago, I built a new PC. A nice FX-8350 machine with 16GB of RAM, a factory-OC'd MSI Twin Frozr 7870, and a Seasonic PSU. I tried to aim for quality components. This is my full build: http://secure.newegg.com/WishList/PublicWishDetail.aspx?WishListNumber=20837585 I put everything together, and the PC ran fine for a week. Basically no problems. However, the stock CPU cooler was pretty crappy (lots of noise, temps not so great), so I ordered a Cooler Master Hyper 212 Evo to replace it. This is the cooler I bought: http://www.newegg.com/Product/Produc...82E16835103099 I got the cooler today. Unplugged my PC and went to work installing it, doing everything as carefully and professionally as possible: Powered down and unplugged my PC, gently removed the stock cooler, cleaned the goo off the CPU with isopropyl alcohol and a soft cloth, screwed on the new backplate, put a dot of Arctic Silver 5 on the CPU, gently seated the new cooler and screwed in all 4 corners a little bit at a time. Secured the heatsink nice and firm, popped the fan on, and plugged it in. Pretty smooth installation process. But... I plugged my PC back in, pressed the power button, and... nothing boots. The computer definitely receives power; the fans spin up and the LEDs come on. However, absolutely no posting happens. There's not even a video signal. The fans just sit there and whirr away while nothing actually happens on-screen. Puzzling, right? I carefully re-seated my CPU, and then re-installed my cooler exactly the same as before. I also carefully re-seated my GPU and RAM to see if that would help. No dice. I power on the computer, but it still refuses to post or give a video signal. What do you guys suggest? Keep in mind, this PC was working 100% fine last night. Installed a new cooler, and now something's totally borked. I've checked all my connections. Everything seems to be receiving power where it should be. Like I said, the cooler installation was trouble-free, and I can't think of anything I did that would've totally borked it. Please give me suggestions, anything at all. Even if it's really simple. I might be overlooking something stupid, but I just can't think of anything. I reset the CMOS. I reset the battery. I tried unplugging the machine again and holding down the power button for 30 seconds, because that supposedly will discharge the PC of any static build-up or something. But that didn't help. I also don't believe I dropped anything inside the PC that would be causing a short. I'm extremely cognisant of things that I drop or misplace; I would've immediately noticed a screw being lost or dropped inside. (But then again I'm not 100% sure.) I hope my motherboard isn't broken.