Well I'm not OC'ed at the moment and lapped and I get 30c Idle with my H50. That's pretty solid considering that a stock 955 BE runs about 42c at Idle.
If he's running stock and depending on his ambients(humidity playing a factory like it always does) 39(+10)c isn't a bad temp. The thing to do though as Sandman says is to play around with the H50 a bit and see which gives better temps. Intake or Exhaust. Front, Top or Rear mounting. I have mine set up in the top/Exhaust with the stock fan carved out and only the housing remains working as a shroud between the Pusher fan and the Radiator which improves flow over having the pusher fan mounted directly to the Radiator. I've included a few pics so you can see what I did.
going to try
top fans off
side fan reversed
h50 in top
will report back with differences. just need buy a thermometer for my room
i tried the temp things i got with my board beteween the cpu and h50 and got -30 you think i could put wrong way round on connector cos i could use these
sorry 4 long post