Your Opinion: Mobo dead?

I have a GA-965P-DS3 mobo and a Q6600. My syystem started overheating and shutting itself down, so I looked inside and noticed a covering of dust over the heatsink. I bought that can of air and some new grease for the heatsink/cpu. I took everything out, got all the dust out, and put it back together.

Now the system doesen't seem to post or beep. Nothing is displayed. The power goes on just fine and all fans are running, HD's spinning, etc, but there seem to be no BIOS.

What do you think: did I kill my mobo when I put the cpu back on it? I hate how hard you have to push down on the heatsink screws to get the thing in.

What should I try before I order a new mobo?

Thanks!

I removed all cards except video and tried switching the RAM around. No difference.

I put just a small amount of grease on the CPU cause I always hear about how people put too much on.

I will take out the CPU again to take a look at it again.

I don't see a speaker on my mobo, does it have one that I can't see? My case doesent have one, so I might have to go buy one so I can hear any beep codes (if there are any...)

Any more things to try?

Did you remember to plug everything back in? Make sure you didnt knock off any jumpers.

You know that 12v cord that comes from the PSU to the motherboard? Well, whatever that thing is for (maybe to power the mobo's BIOS functions?), it is essential. I didn't realize that the plug can be detached from the PSU (they used to be hard-wired in), so when I unplugged it from the mobo, the whole wire came out! It had come unplugged from the PSU! Plugging that in was all I had to do to get it going again.

Thanks to all who posted their help!