XPS 8940, Heatsink replacement

@sc-walter    Seems like it would fit and clear the memory, any thoughts?

Are you having heat issues with the OEM heatsink? What are your computer components (CPU, graphics card, PSU, RAM)?

The Noctua NH-U12A is 158mm in height. The XPS 8940 is 169mm wide to the outside edges of the case. With the mobo being off-set from the back panel, and the thickness of the CPU, I think it is going to be a really tight fit. Be sure to use an extra thin layer of thermal paste 

(click photo to embiggen)

No issues yet (it's not even working properly just yet!) but I expect them.  I do a lot of heavy video and 3d rendering and it taxes the heck out of the system, so I usually refit my systems with beefier cooling asap.

Given the specs, I may shoot for something shorter!

Thanks!

@sc-walter    Given the specs, I may shoot for something shorter!

Have you considered liquid cooling your CPU?

No, this system is basically going to have one job and its going to need to be as basic as possible while still being able to get the job done.  Swapping out an air cooler is simple, setting up one of these cases for liquid would be a project I'm not ready to tackle.

Thanks though!

We probably have the same 10700 CPU without K.

Today I managed to change the stock intel heatsink (not exact since DELL may customise the heatsink by adding screws to mount directly to the case) with this one: Cooler Master Hyper TX3 EVO CPU Cooler.

I can confirm the size fit perfectly (looks like about 2cm touching the case cover) (also means any other heatsink higher than this prob won't fit in the case). It realised some 3 to 10 degrees differences under no load to gaming load average so far (1 hr already), and super quiet coz the fan comes with TX3 is larger

The Cooler master heatsink comes with 4 legs, you will need to use the LGA1155 locations to install those legs (the screw holes match exactly the mount since it uses standard LGA1200 mount hole locations - same locations as LGA1155). So the intention is to just remove the stock heatsink/fan and replace with TX3 EVO.

To install there is ONE challenge only, you will probably need to prepare 4 screws, that's all.

The TX3 heatsink is intended to replace the standard intel stock heatsink which uses plastic fasting mechanism to do the work. The DELL one, even though looks like the intel stock one, used spring tension assisted screws instead. You won't be able to just take the DELL screws to use on the TX3, they are different lengths, unfortunately. What I did was remove the plastic fasting mechanism from 4 metal legs of TX3, found 4 screws that about 2 cm in length (DELL ones have the same thread like the ones on TX3 btw). Then I also found 4 washers together with the washers on the DELL heaksink to suspend the spring and then fasten my screws through the TX3 legs into the DELL motherboard. 

Next step, I am thinking of adding a fan and make the single case fan bigger to further assist the air-flow.

I kind of disagree with people here commenting about the thermal design of XPS8940 without checking it in detail. there are a few things DELL team got it right (including the clever front air intake design - not so obvious if only look at photos). Also, I am not too worried about the custom power supply, to be honest, smaller in size, it helps the airflow close to the GPU. P.S. I do have the GPU swapped with a half-length 1080 in the AORUS gaming box already. Unlikely I would upgrade to RTX30xx something so 500W is sufficient.

Thanks for confirming the TX3 fits into the XPS 8940 case.  We were discussing it in this thread.

Video by @Noorss here using that Cooler Master TX3 120mm cooler into the G5 case which is similar using the M3 bolts which he shows pictured.  Did you do anything different than he did which would be helpful for others using that cooler in the XPS 8940 case?

Good work!

Sounds good and that's another creative way to accomplish the installation. 

@Noorss used a M3 x 10mm bolt with M4 and M3 washers.

Motherboard
TX3 Mounting bracket
M4 washer
M3 washer
M3 x 10mm bolt

You installed using

Motherboard
TX3 Mounting bracket
Dell heatsink washer
Spring
Dell heatsink washer
M3 x 20mm bolt

Is that correct?

Should be no problem using the spring loaded bolts, just tighten down till snug and tighten till it gets a little harder to turn.  As long as you aren't getting any significant wobble in the top heavy cooler when you put the case/motherboard on it's side you should be gtg.   

Again, good work!!!

Thanks HanoverB,

Indeed the video provided a good visual reference (I wish I would have seen it befor I started, luckily no drama).

The major difference is that I don't let the new screws fasting the tx3 mount legs directly. I considered it reduced the required tension for a good fit. I actually reused top washer from the dell heatsink and its spring. The four screws I used was longer (about 2cm, can go 2.5 max prob easy to install). The screw go through one washer on top, the spring, then another washer before fasting the tx3 mounting legs. Hope that makes sense.

I actually measured the height of the spring under max tension on the installed stock dell heatsink to determine how much tension I should be apply in the new installation as well. Don't have to be that precise I guess, aiming for 5mm out of a 2cm screw @ into the base hole should do it.

pretty much so. I broke the bottom washers from the dell heatsink to take its spring out. so I only got 4 of the tops ones. I found other spare 4 washers to stop the spring that gonna press the tx3 mounting legs (prob m3+m4 will do as well I guess).

yes agreed. tx3 is not a heavy duty heatsink. with 4 mounting holes it is rock solid with just a bit of tension.

At least the TX3 can be installed without modifying the backplate and thanks again for confirming that it does fit inside the XPS 8940 case..   

It is still a a 92mm fan based air cooler, but definitely an upgrade to the stock cooler.

@mignonsys 

You saw my rant about how Dell blocked the airflow through the upper part of the front bezel next to the USB/IO unit by making it a solid piece of plastic.   That upper intake position would have been the perfect place to put the Corsair H60 CPU liquid cooler since you can move the HDD to the upper bracket. 

I have a question about the airflow through the lower part of the bezel....does it actually indirectly flow to the upper part of the bezel under the solid piece or is there a piece of plastic that would block it?   There are no airflow channels through the side of the upper bezel which they could have done, so I am assuming that very little air can get to that upper intake position?  That is how it looks when looking at the pictures.

I was able to find a picture from this section of the manual

It looks like there is a piece of plastic impeding airflow across the bezel to the upper intake position.

Wondering if that is indeed what it looks like on the actual case.  Picture would be helpful.

@mignonsys    Are you going to change the airflow direction of the rear case fan also? if not, are you going to have a case fan pulling air out and the liquid cooling radiator fan pulling to front?

The radiator fan in the top front position would be intake . . . pushing cool outside air through the radiator and back to the rear exhaust fan. The air flow is 'front to back'.

For the money I'd spend on Liquid cooling, I'd better get a blower fan-based CPU instead.

I don't think the XPS 8940 has a 'blower style' CPU cooler option like the XPS 8930 did. Of course, that exhausted out the top of the case. The Corsair H60 Hydro Series AIO liquid cooler is $80.

@HanoverB 
Just saw your post about putting a liquid cooling radiator and fan on the top front position. 
Are you going to change the airflow direction of the rear case fan also? if not, are you going to have a case fan pulling air out and the liquid cooling radiator fan pulling to front?

If the radiator fan is puling air front, how you can ensure the warm air not cycling back into the case from the bottom part? 

After I swapped the stock headsink for my non-K 10700, the CPU has rarely reached 70 under even heavy load. I won't add liquid cooling. The area I consider can improve would be the air flow from the bottom front to the top rear (so no circulation back for sure). It can help address the GPU open cooling heat, and the components heating up close to the CPU like the M2 SSD and WIFI card. For the money I'd spend on Liquid cooling, I'd better get a blower fan-based CPU instead. 

@HanoverB ,

Sorry, I made a few typos in my reply, I am referring to the heated area around GPU not CPU.
I was trying to say that I would save some money, purchasing an equivalent graphic card with blower type fan :-). It has been my concern before kicking off any real workload, as I am still using an open-air 1080, everything near it was still a bit hot (M2 SSD reaches 60 to 70 degrees - hotter than GPU - without heavy read/write).

The CPU temp has been managed well so far with just the TX3 air cooler.

Question for consideration, if you direct the cool air through the radiator, would it be warmed up, then gone through the memory modules the top of cpu and potentially voltage regulator, before getting sucked by the case fan out?