Weird Drop in Hash rate

[merkin]

 

Hi there, I just applied some new thermal paste (Arctic Silver 5) to my 2 x GTX 560Ti cards

I've had success with lowering the temps in this way before but this time it seems they've stayed the same and possibly gone up a couple of degrees :[
Including my idle on one card

Anyway afer running CUDAminer I get my normal hash rate of around ~300-320 khash/s but then 30 seconds later starts to drop to around 82, and 92 khash/s for each card totalling around ~170khash/s

Does anyone have any idea what could be happening? maybe my cards are running too hot and skipping a beat?

Help  

[merkin]

Howly shit , it was definitely the temps that was doing the harm

I took the card out and checked if it was sitting right on the dye correctly.

and it wasn't.  This heatsink seems to need more paste it's a weird design and is it's raised up a bit on the sides and can't directly sit on the dye
but sits on the bits that stick out.. :O