Does it matter what Thermal Paste I choose? And if it does which is the best?

[Hawksider]

Everything is in the title.
Quick note: I am not building a PC, just asking this question to learn.

 

[krzyimprt]

Everything is in the title.
Quick note: I am not building a PC, just asking this question to learn.

Not really. If you buy a third party cooler they always come with thermal paste, same with stock air coolers. Skylake and Kabylake CPU's that have a K at the end do NOT come with coolers.

 

[Dooop805]

It does matter. There's a handful of good ones, I use MX-4.

 

[Aspiring techie]

I'm assuming you mean thermal paste for a CPU.

It doesn't matter much which type of thermal paste you use with regards to cooling. The difference between products is maybe 1-2C. There are certain types of thermal paste to avoid. Some almost act like a glue and bond with the CPU and cooler, making it nearly impossible to separate them.

As far as what one is best, there is no good answer. It ultimately comes down to personal preference. I prefer to use Arctic Silver 5.

Toms did a really in-depth study on thermal paste. Here's the two articles. I think you will find them most helpful.
http://www.tomshardware.com/reviews/thermal-paste-heat-sink-heat-spreader,3600.html
http://www.tomshardware.com/reviews/thermal-paste-performance-benchmark,3616.html

 

[MeanMachine41]

Everything is in the title.
Quick note: I am not building a PC, just asking this question to learn.

As you have a thirst for knowledge that's good and you've come to the right place.

A commonly asked question is what to use and how to apply TIM. (Oils ain't Oils and TIM ain't TIM)

It does make a difference as to what you use and how you apply it especially when Overclocking and can be a difference of 10C.
I use either AS5 or MX4 which have very similar thermal conductive properties. A TIM is good if it is like grease in consistency and not a thick oil. It should be applied as sparingly as possible to fill just the tiniest of Voids. TIM should not squeeze out the sides of the thermal plate as it can cause issues and applying too much will deplete thermal efficiency.
The most common practice is to apply a small pea sized blob to the center of the CPU and tighten down the brackets in a crosswise pattern in incremental steps and only finger tight.
Most pre-applied pastes are OK but I personally clean it off and meticulously clean both surfaces with Isopropyl Alcohol 95%. I'm probably a little pedantic as I will lap the CPU ground surface if its too coarse.
To get it right for first timers its best to have a trial run, apply then check the spread.

The Good TIM contains metallic oxides and not electrically conductive although if excessive amounts are used it can provide an undesirable conduit bridge to components on the MB.


For those technically inclined, TIM is rated by its thermal conductivity.
Thermal conductivity λ is defined as the ability of material to transmit heat and it is measured in Watts per square metre of surface area for a temperature gradient of 1 K per unit thickness of 1 m. W/mK

Some of the best TIM on the market
AS5 = 8.9 W/mK
MX4= 8.4 W/mK
Thermal Grizzly Kryonaut=12.5 W/mk
Some pastes are only 1.2 W/mk and should be avoided.
Some pastes harden and become an adhesive causing damage when thermal plate is removed.

Here is a listing of many TIM pastes to evaluate: http://overclocking.guide/thermal-paste-roundup-2015-47-products-tested-with-air-cooling-and-liquid-nitrogen-ln2/11/