I had a little idea about increasing the surface area of the ihs. How about lapping the ihs, then applying lots of tiny little blobs of copper paint. The conductive stuff that you can get to repair car window demisters, which used to be needed to unlock some cpu's and even small amounts of vmodding. I'd say have a grid of dots, maybe like ~half the ihs surface area. Next it would be great to scrape the ihs between each of these dots, so as to roughen the ihs maximising surface area. After this, clean and apply another layer of blobs ontop of the original blobs, so that they are now twice as tall. This can be repeated until a nice height is obtained, say i dunno, a few mm would be awesome, but a couple of mm is probably good enough? that's probably anywhere from 5 - 10 layers? The stuff dries pretty quick so it's not that much work really, the copper paint has a high % of copper in it so they will conduct the heat really well, and you have alot more surface area for the water to extract heat from. You'd probably wanna do this on a prescott Unless you don't scrape the ihs, just use blobs of copper, and it can always be lapped off at the end of the experimenting, leaving you a flat ihs. I dunno about how much pressure is needed for the o-ring? There's a couple of links here that will have good info for ya.