Thermal Paste dries out? Is that a bad thing?

For some reason my dear Phenom II X6 1055T is no longer stable at 3710MHz (265*14), 1.525V. No prob, never really needed the extra speed, I suppose. Went back to stock clocks.

And now my GTX470 with its Gelid Icy Vision Rev. 2 is crashing my computer. Before it would never ever crash at 770MHz/1087mV, but somehow it just did while folding. And temps at that speed skyrocket to ~88C, which I’m pretty sure was not what I had at first, otherwise I wouldn’t have been impressed by the product. I checked my old forum postings, it seems I got 40C idle and 60C load with the Gelid. Now, it’s 50-54C idle and 73C load! This needs to be rectified… tomorrow. Until then, back to stock clocks.

And when I put stuff on top of my case to defrost it, that somehow makes it go up a few more degrees, causing it to crash.

I asked an overclocker I met at CeBIT, he said that the thermal paste must have dried out. Although I don’t see how that would fix the CPU instability, because temps never changed, I do think the Gelid would benefit from some new thermal grease. I just have to remember which damn paste I used before so I don’t use it again… was it the one that came with Gelid, or was it the Arctic Silver Ceramique?

EDIT: Just took it apart, put it back together again, putting the Ceramique in a plus pattern, instead of the X pattern I used when I first got the heatsink. I had used the thermal grease that came with the Gelid thing, which was ok, but it wasn’t spread evenly. And I think I just used a dot pattern with it. Now idles at 45C, load 68C, overclocked to 770MHz/1087mV 80C. That X pattern couldn’t have helped that much, could it? Hmm.