I researched this last year and read a dozen + sites and came to the conclusion at that time the
Gelid Solutions GC-Extreme
Was the best choice for:
- Consistently among the highest rated / suggested ones
- Consistently had cooler temps (and cooler temps than my previous AS5 paste)
- Non conductive
- Easy to use/clean
- Somewhat still affordable for building dozens of systems
I was using Artic Silver 5 (at-least I think that's what it was 2 or so years ago) previously but for a few bucks more the GC was getting 5*C cooler avg or so on
all review sites I read.
Right off the bat you eliminate the insanely expensive ones, and the pain in the rear ones which are usually the top 1-3 pastes that people rarely use due to 1 or more of those issues, the next elimination for me was anything conductive in case I made an "oops" and didn't notice. The next thing I looked for was cost to saving... for me it wasn't worth even $2+ more to save only 1-3*C.
If sound isn't a concern then there's probably no point in going with anything that cost more than AS5 because the fan will compensate for the difference at idle, and at load the fans already at speed and it's not like 5*C or 15*C at load is going to ruin or degrade the CPU before life is up.
This is purely from a server / workstation perceptive, if you're OCing and pushing thermal limits then 5*C may matter to you much more than me / most of us