If you are using the stock intel fan, thats what my gut thinks the noise is comming from. Try a different one if you can. It's gotta be a fan, I've never heard of the board itself making any real noise, it's always a fan.
Opteron 175 + Scythe Infinity
2 gigs corsair XMS DDR 400
XFX geforce 6800 XT
30G Maxtor + 250G Maxtor
"Let's face it, we're not changing the world. We're building a product that helps people buy more crap - and watch porn." -- Seagate CEO Bill Watkins