I am not a fan of metal TIMs (e.g. AC AS-5 or coliul), one false step and suffer consequences later ... not funny. always was thrilled when using AS-5 in past.
ICD works amazing, however it does scratch the surface of CPU even in short term (application, use, removal), pretty much I use it only on chipsets if needed. only problem with ICD is that it's a b***h to apply it evenly, this stuff is so thick, that you won't be able to squeeze it out syringe without warming it up first ... and it doesn't stick to metal very well, I always used a piece of old plastic card to spread it thin across IHS, was taking lots of time but it was working. removing that stuff later is another story (royal PITA!).
I started to care about CPU scratching after I purchased intel's overclocking warranty for my 2600K chip ... lapped surface = voided warranty.
started using Shin Etsu X23 on CPUs recently and I am very happy with it. it joins the soft structure of MX-2 (X23 is a bit thicker than that) and awesome properties of similar class as ICD provides.
used MX-2 in past and this TIM worked nicely, however it turns into a useless goo after roughly 3-6 months of 24/7 use, calling for removal and re-application. not fond of it. I heard that MX-4 is not much better.
have a syringe of EVGA's Frostbyte somewhere too, but haven't tried it yet.
bottom line is, I stick to X23.
I am not eager to try Prolimatech PK1 or indigo xtreme as both are electrically conductive substances (metals in ingredients) and I personally don't like this fact.
<message edited by feniks on Tuesday, May 01, 2012 11:43 AM>