1. what are the ambient temps?
2. as suggested by moksh4u2, what were the idle temps on the stock cooler?
3. What thermal compound are you using?
4. idle temps below 30 can be achieved only if ur ambient temperature is around 18-20 degrees.
5. no matter what ever cooler u use, it cant lower the temps below the ambient temp.
6. are the idle temps monitored with Air Conditioner on or off?
7. check whether CPU is running at stock speeds, and cpu voltage is set to auto.
i am sure u have the answer for ur high temp issue in one of the above points.
cheers
Vrishi