What price performance? That's the question you always have to ask yourself when considering Intel's uber-expensive Extreme processors. For the QX9650, the answer, sadly, has to be too much.
Largely that's due to the arrival of the much cheaper Q9550 model. An extra £400 is an awful lot of money to pay for the 170MHz of additional clockspeed and unlocked CPU multiplier the QX9650 offers over its cheaper sibling.
In all other regards it sports an identical 45nm quad-core feature set. In our testing it wasn't even much quicker for overclocking - 3.5GHz plays 3.4GHz.
What's more, if you are going to spend an insane amount of money, it makes sense to go the whole hog, bag the QX9770 model and enjoy the knowledge that you've managed to buy the fastest processor possible.