Best heatsink upgrade for Dell Precision T3620 with Intel i7-7700K CPU?

tbh those are fancy tower coolers that are harder to install than the Dell premium cooler because of gigantic size of heatsink which may impair access to ram.  If you prefer ease of installation and small foot print, then a Dell 120 mm or 240 mm AIO liquid cooler is better option which can keep the cpu cool.  Dell uses M3 back plate.  those fancy air cooler use their own backplate.  you would need to remove the motherboard, somehow remove the Dell backplate (not trivial as you may need to remove the CPU ILM first).  It is an adventure not necessarily worth embarking on.

Less chance of fan errors at startup if you use a/the Dell cooler.

It looks like some people upgraded the CPU without thinking about the cooler/heatsink.

@redxps630​ I didn't realize that there was that wide of a compatibility gap. I definitely don't want to do anything as drastic as the motherboard removal, etc, that you described.

I can't find where to buy those Dell liquid coolers that you mentioned. Do you have any links? Are they much more expensive than Noctua's tower coolers and/or prone to leaks?

Are they much better than the VWMTJ? And are there any other (perhaps newer) Dell heatsinks (air-cooled or otherwise) that are backwards-compatible with my machine?

@bradthetechnut​ So am I correct in inferring that Dells often don't play well with third-party fans?

A 120 mm liquid cooler is cheaper than the high end Noctua ones I think, unless you find a used one on sale at much lower price than new stock.  In general a high end fancy third party tower air cooler can cost upward close to 80-90 usd if it is indeed a high performance type.  Dell did not design an AIO for Precision afaik, the AIO are for XPS and Alienware.   

First find out if you have the 95 or 65w heatsink in it already.  65w no good. Needs to be at least 95w.  Here are all coolers from Dell for 3620

Use the service tag of pc go to Dell product support website, type in tag, then look up View Product Spec.  Look for spec of heat sink originally shipped in this pc, assuming refurbisher has not changed original heatsink.

The 65w heatsink is a thin pancake, whereas the 95w is a thicker taller pancake.  This pic of pc having i7-6700 cpu seems to have the thin 65w cooler

@redxps630​ I have the 65W one. It's what was originally included with the computer, but the refurbishers upgraded the CPU to an i7-7700K without also upgrading the heatsink.

I have now ordered the VWMTJ from the link you provided. Thank you for providing that link; I had no idea there were any still available new rather than used, especially for that low a price.

The only bad thing about that is that it doesn't come with pre-applied thermal paste, so there'll be guesswork involved regarding how much to put and in what pattern.

Do you have any recommendations for best brand/type of thermal paste to use and/or any good tutorials showing how best to apply it?

Also, do you know what the best type of removal kit for removing the current paste is? I've seen various kits that come with ArctiClean and various tools (sometimes a sort of plastic spatula, sometimes a lint-free cloth, etc). Although some people say they just use coffee filters and 91% isopropyl alcohol.

Just 91% rubbing alcohol and any clean tissue paper.

no need to go fancy on thermal paste.  You are not trying to break an overclock record.

apply only a small grain size like a grain of rice to center of cleaned cpu then mount the cooler on cpu in one motion, tighten 4 screws diagonally.  If you accidentally lift up the cooler, then do it over again

the key is to let mounting of heatsink spread the paste to as thin a layer as possible to fill the microscopic imperfections of flat surface of cpu n heatsink.  Dell factory almost always applies a thick layer which is a bad idea.

@redxps630​

apply only a small grain size like a grain of rice to center of cleaned cpu then mount the cooler on cpu in one motion

What about this method of spreading the paste with a small specially-designed spatula? Could that help ensure an even application?

no, that is not necessary.  there are all kinds of school how to apply paste, some do multiple dots, some cross shaped.  it is much ado about something very simple.  just let the heatsink spread out the paste from one dot centrifugally.  in the end common user experience does not make a difference as long as you are not doing something glaringly wrong.  no need to split hair what is the best method here.  move on to enjoy your pc.

@redxps630​ Is it necessary to make any changes in the BIOS, or should the new heatsink and its built-in fan be "plug and play"?

Dell heat sink fan 65w, 95w, premium tower is plug n play.  No bios change needed.

@redxps630​ Good. That's one less thing to worry about.

Thank for all of the advice. The heatsink and some Arctic MX-6 should be coming in this week. Hopefully the replacement process goes smoothly.