yea good look lol you cant hit 5ghz with a qx9650 with watercooling, 4.5ghz is possible with reasonable voltage, look at the rankings on hwbot anything over 4.5ghc with ure processor is with dice or phasechange or ln2. try useing a 10multi and then 450mhz on ure fsb with 1.5vcore, erm i suppose u could up the ram speed also useing a divider.
well it isn't any more difficult than getting it to 4ghz. You increase the fsb little by little, you test every step of the way, you increase vtt/vdimm/etc when it isn't stable anymore... Depending on the vid of your cpu, you might need more voltage than you'd think is safe. I've seen q9650 go up to 1.5-1.6 so don't worry too much for your qx.
well for 4.5ghz you can use a 10multi and a 450fsb then a 1:1 mem dividor, that would make ure mem run at 900mhz, if u use a 2:1 mem dividor then ure mem would run at 1800mhz which will better utilize ure fast mem.