Zalman 9900 Max CPU Cooler, Bad temps?

Hi,

Just bought a Zalman 9900 Max CPU Cooler in hope of reducing my Temps.
My CPU is a Core 2 Quad Q8400

I applied Arctic Silver 5 using the horizontal strip method (as directed on the website)
I did not use very much thermal compound just a thin line across the two cores.
I did not tint the CPU.

I'm meant to be getting idle temps of about 26- 30c ( based of all of the cooler reviews and tests.) But I'm getting 40c Idle.
Which is no improvement over my old cooler.

Arctic Silver say the break in period for Arctic Silver 5 is 200 hours, and i should get several degrees drop in temp. But that still would only get me to about 34 c?
I've tried it on the silent and performance mode (using the resistor) makes no difference.

( My case cooling is is fine with 2 exhaust one top and 1 back and 2 front intakes, All 140 /120 mm fans. )

Any suggestions?

Thanks