Core 2 much hotter than 1?

I have seen this in other CPUs as well. Normally just a temp variance because the core is being used.

But for it to do that in a chip thats a dual core by 10 degrees you may want to check your HSF and make sure it is seated right and tight on both sides.

Odd thing is its the core thats not being used thats hotter load is 7% ! i know the heatsink is very tight, im monitoring it as i hear it takes a while for the arctic silver to reach optimum cooling, i have took my case lid off for the moment which has dropped temperatures. Its ok in normal use but when running a stress test it shuts down.

Well.. to have a faulty core, is to have blue screens. To have a faulty sensor is different, and perhaps what your experiencing. Since your using a 6400+ BE chip, its not clear how the temps are determined.

Having the HS tight is one thing, but even pressure is another. I'm guessing your using a tower case, so the Zalman would have more pressure on one side of the CPU. Have you tried laying it on its side so the weight would be more even?

In my experience with AS5, I'm sorry to say the cure time didin't really have any affect in decreasing the temps for any of my past applicatons. The only profound effect I saw was when my ambient temps were cooler. So in my mind, I kinda wonder if people over look that, and mistaken the cure time made the CPU temp cooler. I generally use MX-2 since it doesn't have a cure time, and is supposedly good for 7 years when applied.   . o O (don't think I'll have the HS on that long)

Since you mentioned the stress test causes a shut down, but is cooler with the case side off, I can only assume that your airflow is constricted, and perhaps your ambient temps may also be high.

Its lying down, its a small atx case, im just lookin at mouting an extra intake fan, think im going to remove my cd rw, a stick of ram (ram is actually touch the cooler!) and try fitting a new intake fan at the front, re sit the cpu and go from there, failing that ull just leave the sides off !

Its fixed ! just got through near an hour of stress test no shutdowns would not last 10 mins before, i think that one stick of ram was stopping the heatsink sitting correctly, its around 38 degrees idle now and around 55 under full load, it was 80 before under load! hence the shutdown! cheers people

Grats.

Having the HS sit totally flat on the cpu would be.. important.  

it looked flat but it obviously was not 100%! as the temps totally changed after i removed that stick of ram, only got 3gb now though !

^Which Zalman do you have? One of the flat ones?