5punk

Ran a system test cos I was bored using http://www.passmark.com/products/pt.htm

Note in the Memory section it's saying I have 4x 1024Mb 800MHz RAM.

Now I know for a fact I have 4x 1024 1066MHz Corsair Dominator RAM plugged into the MOBO, can anyone enlighten me on why it might not be running at full speed?

Mobo may not run 4 sticks at 1066. A lot of mobo's that are advertised as capable of 1066 can't do it for a full set of memory. A lot of them don't even like accepting four sticks despite being advertised as such.