If it is your mobo, why not lift everything out and do my 6 months treatment:
what is needed:
a lint free cloth (yellow duster, e-cloth etc)
tweezers
kitchen towels
compressed air
rubbing alcohol
what to do:
take everything out of your case and wipe the case down with the cloth, that includes taking off any front, top or rear panels, you would be amazed how much dust they collect. So long as you have no fans or hardware in there, you can even hoover your case to get the worst bits away, static don't hurt the metal case, but can potentially hurt components, so don't use it on them!!
Take the heatsinks off everything and clean under/around it, that includes video cards, processor, northbridge etc. dont put thermal paste and stuff back on yet, but do wipe off the worst with the kitchen towels and put some rubbint alcohol and rub it and that to get rid off the thermal paste that you can't see.
Clean inbetween all the stuff, this is where compressed ait and tweezers are best to get in the fiddly bits.
make sure your heatsinks and chips are now totally dry, when they are, reaply thermal paste, put it all back together and it is good as new.
If you take care, then you will need maybe 3 or 4 hours to do a proper job of it
