Just in case anyone is thinking of buying this to quieten their PC. For your £12 - £15 (dependent on where you get it) you get 4 sheets of foam. You then half dismantle your PC to fit it properly. In return you get maybe a 1 - 2% reduction in noise and a smell that'll make you retch. After three days the smell is as strong as ever. I'm going to have to buy a new case as, once stuck down, this stuff is almost impossible to remove (I've tried) and the smell is intolerable. Avoid like the plague (this stuff smells like the plague).
I've got it inside my system, and it doesn't smell at all.
Maybe your pc is running like an over, and its giving the foam a roasting?
Can't say I noticed much/any reduction in sound though.
In my seemingly futile quest for coolness/quiet, I have added a load of stuff to my pc. This includes a quiet psu from quietpc, a zalman silent cpu cooler, a zalman silent gpu cooler, a seagate ultra-quiet (as they're marketed) drive, 4 silent case fans from quietpc all contained in a Lian-Li 7 completed padded with the akasa foam - guess what - still plenty of noise.
I've recently come to the conclusion that my pc could run quietly - and the main thing that seems to generate a lot of noise is the actual case, reverberating. I worked this out my adding to pressure to various parts of the case, and notice the high pitch sounds stop. I now have both side panels of my case off, and just leaning up against the case. This is probably a bit bad for the components, as I imagine a lot more dust can get it - but it is bizarrely a lot quieter - although i have to live with my nice aluminium lian-li case looking like it's broke or won't fit together or something