poor performance from taisol with copper base

I recently bought a taisol CGK760092 heatsink to replace my fop 38 but too my amazment it performed worse than the fop 38 even with the delta fan.

However when i remove the heatsink normally an perfect imprint of the cpu core can be seen but in this case there is very little arctic silver where the eges of the core meets the heatsink andquite a large amount in the middle.

i have checked the flatness of the heatsink and it seems concave i have tryed to lap the base but so far it has not made much difference it is hard to tell whether the base is flat does anyone know any easyways to check for flattness.

What else could be causing this?

any help would be appreciated

is the taisol suppose to work better than the fop 38, cause i always thought the fop 38 was a good heatsink. um copper base and good contact, i can't see what the problem was. did you use a 4 pin or 3 pin connector for power?

what are you on?

this heatsink is the best one that taisol make and the fan was working at full capacity anyways it was the sam fan as i was using on the fop 38 which is one of the oldest heatsinks globalwin make.

What temps are you getting with what prosessor? And what did you get before?

My Taisol (same one, with copper, I don't remeber the model) will get my AMD 1.33 GHz to idle 38 /load 43 with ambient 21. I checked flattnes with a ruler held to the base and looking toward a lightsource to check for any gaps, but didn't find any.

Oh, and I'm using a 80mm fan on it..

Is the heatsinks base smooth enough or are their any machine marks on it?

i have lapped it and there no machining marks on it