Help, upgraded my PC and when turned on gave a burning smell...

[NukaCola]

These are the parts I got:
G.SKILL Ripjaws X Series 8GB (2 x 4GB) 240-Pin DDR3 SDRAM DDR3 1600 (PC3 12800)
http://www.newegg.com/Product/Produc...82E16820231428
Intel Core i5-2500K Sandy Bridge 3.3GHz (3.7GHz Turbo Boost)
http://www.newegg.com/Product/Produc...82E16819115072
ASrock Gen3 Z68 Extreme3 mobo
http://www.newegg.com/Product/Produc...82E16813157271
XFX Radeon 6950 HD Dual Fan
http://www.newegg.com/Product/Produc...82E16814150549

Basically I upgraded from an older build, but I kept the same PSU and case. PSU is OCZ Gamestream 600W.

So I followed the motherboard guide and New Egg computer building video tutorial, starting with mounting the motherboard, added I/O shield, (used 7 mobo mounting screws, made sure none of them were unaccounted for/touching the underside of the motherboard, used 7 screws to screw the motherboard into the mounts, and not too tight). Then I put the CPU & heatsink in, which went fine. Then went RAM and video card. Video card was a bit difficult to fit due to size but with enough of a hassle it fit.

Then came SATA/power SATA cables from the PSU, USB plugs, power button and LEDs, and all other necessary power cables needed for the mobo, graphics card, and fans.

When I was ready, I plugged in the power cable, video cable, USB mouse and keyboard, and audio plugs, and hit the PSU switch on the back. Almost immediately I smelled a burning smell. After 2-3 seconds I immediately switched it off and unplugged the power cable. A friend came over and took a look himself, took out the RAM to smell it but there was no burning smell. And there's no visible imperfections on the mobo or anything else for that matter. I unplugged all PSU cables and turned the PSU on to test it, and there was no burning smell.

What could be the issue here? Have I shorted the motherboard? I seriously don't understand how, as I checked everything and followed the mobo manual closely...

I'm too paranoid to turn anything on again, so I will be waiting for my friend's father to help me out either Friday or Saturday. I would just like some input and suggestions. Does a burning smell mean I just flushed $640 down the drain? I seriously hope not. I'm not a stranger to building PCs. This is my 3rd upgrade. I appreciate any advice/help. Thanks.

EDIT: Also want to mention that I did not notice an LED turn on on the mobo, but then again I didn't have time to notice because as soon as I smelled something I immediately turned it off and unplugged.

 

[Motorheader]

So nothing was touching - no grounding with knockoffs on the motherboard tray, etc? How about one of the nasty little metal pieces that are around the USB ports (or any of the rear ports for that matter). Sometimes they can inadvertantly get pushed into the port itself when the motherboard is installed.

Do you a different video card available for testing purposes?

I've seen where the screws/plate for the cpu cooler on some setups stick out enough to touch the motherboard tray causing various issues.

 

[Gillbot]

If you have it in a case, take it all out and inspect it thoroughly to look for burn marks or other signs of failure. f nothing is found, assemble it on a table preferably on cardboard or something non-conductive. Check from there.

 

[NukaCola]

I'm going to have my friend's father take a look at it. Perhaps he can notice something that I can't. We'll have to reassemble everything and see if that will do anything. At the moment I won't be checking each individual part but I know that there are no noticeable burning marks of any kind.

 

[THRiLL KiLL]

use your nose to tell where the magic smoke was released