Different TIMs will vary in performance by as much as 5C. Applications methods can produce similar variations. two of the best / most comprehensive articles every written are here" ... and tho a bit old are still relevant.
80-way Thermal Interface Material Performance Test
http://archive.benchmarkreviews.com/index.php?option=com_content&task=view&id=150&Itemid=62&limit=1&limitstart=12
Best Thermal Paste Application Methods
http://archive.benchmarkreviews.com/index.php?option=com_content&task=view&id=170&Itemid=38&limitstart=5
Since then, the two major development of "changes in the TIM landscape" have come from :
"Liquid metal" TIMs introduced bu Collaborartive Labs or "CoolLaboratory". This are not recommended for novices but are the pinnacle in TIM performance
http://www.coollaboratory.com/
New products "....naut series" from Thermal Grizzly. These edge out the top products from the 80-way review but come up short of the Liquid metal stuff.
The main issue with the Liquid metal stuff is that it is conductive... so splling a drop on your MoBo or somewhere would be a bad thing.
The two top TIMs in the 80-way head to head test where Shin Etsi 751 and Artic Silver 5. I prefer Shin Etsu for 3 reasons:
a) Cost - Shin Etsu is $3.88 ... Artic Silver 5 is almost twice that at
http://www.outletpc.com To be fair, you get more product in the AS5 tube but It's not like you are going to put it away and use when you remount the CPU 2 years later.
b) AS5 has a curing time requirement of 200 hours . Even if we leave the puter on for 8 hours a day, that's 25 days before you can dial in maximum OCs. If Im doing a build for someone, and I'm asked to OC the build, I can't have the puter sitting on my workbench for days waiting for it to cure. from AS's web site
Important Reminder:
Due to the unique shape and sizes of the particles in Arctic Silver 5's conductive matrix, it will take a up to 200 hours and several thermal cycles to achieve maximum particle to particle thermal conduction and for the heatsink to CPU interface to reach maximum conductivity. (This period will be longer in a system without a fan on the heatsink or with a low speed fan on the heatsink.) On systems measuring actual internal core temperatures via the CPU's internal diode, the measured temperature will often drop 2C to 5C over this "break-in" period. This break-in will occur during the normal use of the computer as long as the computer is turned off from time to time and the interface is allowed to cool to room temperature. Once the break-in is complete, the computer can be left on if desired.
c) AS5 is "capacitive". Again from As's web site
Not Electrically Conductive:
Arctic Silver 5 was formulated to conduct heat, not electricity.
(While much safer than electrically conductive silver and copper greases, Arctic Silver 5 should be kept away from electrical traces, pins, and leads. While it is not electrically conductive, the compound is very slightly capacitive and could potentially cause problems if it bridges two close-proximity electrical paths.)
I would note that I prefer Gelid Extreme over Shin Etsu for GPU water blocks where you can be applying TIM to over 20 surfaces (GPU, Memory, VRMs ... and on front and back of PCB).
a) It costs more, but you get enough to complete a GPU water block install. Also comes in 10g tube for doing builds with multiple blocks.
b) It retains "spreadability" longer than Shin Etsu
c) It came in only 0.1C hotter than Shin Etsu in the 80-way test but like Shin Etsu, no curing or capacitance issues that hinder AS5.
Thermal Grizzly has 3 products
Kryonaut is the top end @ $23.95 at PerformancePcs.com for 3.0 grams
Hydronaut is next @ $16.99 at PerformancePcs.com for 3.0 grams
Aeronaut is the budget version @ $9.95 at PerformancePcs.com for 3.0 grams
But it in the 1.5 gram tube and prices are $16.95, $9.99 and $5.95 (tho they web site calls it Hydronaut)
Buy it in 1 gram tube and the Kryonaut and Hydronaut are same price at $5.95 ... go figure
I have seen several web sites do reviews of Grizzly Kryonaut and it's won some (edging out Gelid) and lost some.