Dell XPS 8930 is noisy under load - How to improve Cooling - Top Fan and CPU Cooler

Open the active Windows Power plan and try lowering max allowed CPU usage to somewhere between  ~99 to 95%, instead of 100%. Save the change before leaving the Power plan. See if that helps.

And make sure you have latest versions of BIOS, Intel chipset drivers and video drivers which can all be downloaded from Dell's support page for this model..

If you change the CPU fan, you're likely to get a Fan Failure error at every boot because Dell OEM fans have a sensor that has to be read by BIOS.  

The CPU usage for Photoshop Elements is not in itself an issue - it just highlighted the fan noise as the CPU usage went up and down. After I left Elements running on the PC overnight, the CPU usage fell back to normal. I assume that Elements was doing something like building an internal catalogue from the thousands of pictures it was importing.

I would rather not reduce the CPU performance just to make it quieter but i may consider this if I rule out all other options.

I did try changing the chassis top fan for a Noctua "silent" PWM fan (NF-S12A). In practice there was very little noticeable difference in fan noise - but CPU temperatures when ripping a bluray were higher with the Noctua.  (I measured the CPU temperatures using CPUID HW Monitor - free to download.)

Interestingly, I didn't see any BIOS errors reported for the fan replacement.

The stock fan for the 8930 is an AVC DAT1225B2G. It claims an airflow of 148.9CFM.

The fan that I was testing was a Noctua NF-S12A PWM. It claims an airflow of 107.5m3/h.

Putting those in the same units - the stock fan can move around 250m3/h. So it seems to be over twice as powerful. In practice the AVC seems more powerful than any "quiet" 12cm fan. It appears that the 8930 needs such a powerful fan even if it is noisy.

I have also looked at replacing the CPU cooler. The 8930 when shipped with an i7-8700 (which has a TDP of 65W) has the CPU cooler shown on p17 (and lots of other pages) of the service manual:

http://topics-cdn.dell.com/pdf/xps-8930-desktop_service%20manual_en-us.pdf

It looks like this:

however, XPS 8930s shipped with an i7-8700k CPU (which has a TDP of 95W) are shipped with a cooler like the one shown on p85 of the manual and looks like this:

(One issue with this cooler is that it covers the 4pin motherboard power connector - shown on the right of the picture of the standard cooler. This means if you have an i7-8700k and you want to change the PSU then you must remove the CPU cooler to access this socket.) 

So I wonder if it is possible to order this higher rated CPU cooler and fit it too the XPS 8930 with a standard cooler.

Does anyone know the part number for this enhanced cooler?

Alternatively you can try and fit an aftermarket cooler. However, that isn't easy on the 8930. 

Firstly there is the issue of physical space. The existing cooler is a little more than 50mm (2 inches) high. There is only around 20mm (4/5 inch) between the top of that cooler and the side of the PSU. So that limits the upgrade possibility to very slim coolers. Additionally there are some capacitors/resistors around the CPU socket. A replacement cooler needs to have a high enough base to ensure that these are cleared.

I did try using a Cryorig C7 cooler. This is only 47mm high including the fan so it looked like a possibility.

However, I hit two problems with using this cooler. Firstly, to remove the existing cooler back plate you have to remove the CPU socket clamp as it has three screws that screw into the same back plate that the CPU cooler screws in to. The screws are really short and would not reach the back plate for the Cryorig where these holes are a few millimetres from the surface of the motherboard.

Secondly the bottom of the Cryorig is too flat so that the wider body of the heatsink sits on top of the capacitors/resistors rather than the CPU itself. The existing stock cooler has a small block about 5mm (1/4 inch) high that makes contact with the CPU and sits below the main body of the heatsink. This raises the main body of the heatsink so that it clears the capacitors. The cryorig equivalent block is only a couple of millimetres high.

The only other 3rd party heatsink that I have found that looks like a possibility is the Thermalright AXP 100. Which has a block on the bottom like this - so should clear all the capacitors: (Picture is taken of the heatsink when it is upside down):

This cooler is only 58mm (2 1/3 inch) high so should fit. However, it seems to be hard to get hold of as this model seems to have been replaced with a higher spec cooler that is a bit taller. 

If you could go to 65mm high then there are lots of good CPU cooling options but I think that they will probably have their fan too close too the PSU to get decent airflow.

I did also consider getting a water cooler. However, while these take up only a small space above the CPU they require you to replace the case fan with a case fan and a cooling block. Together these are much thicker that the existing case fan and there isn't enough physical space for both of them. (The case fan in the XPS 8930 sits very close to the top of the PSU.)

I had heard before that the Dell Aurora R7 has the same chassis as the XPS 8930 and that has a water cooling option. So looked at buying the Aurora Water cooling kit from Dell ($99 USD). However, the top of the chassis for the Aurora has a large hole cut out of it to fit the fan and the cooling block - most of it sits outside the metal chassis under the plastic top cover. The XPS 8930 does not have this hole. Instead the chassis fan sits inside the case and there are a series of holes in the chassis for this to blow through. I don't want to cut a 5x5 inch hole in the top of my new Dell chassis. :-)

So overall i think that the only options are:

(1) Cut the CPU maximum performance by 5 or 10 percent and see what difference this makes with the high CPU stuff that I do - ripping blurays and VR.

(2) See if I can get the enhanced Dell CPU cooler for the XPS 8930.

Some users said they only had to go down to 99% max CPU usage. So start there and work your way down, if necessary...

I thought that I would test this to see if changing the Max CPU setting in the Power & sleep options would work. (I did my testing using the Balanced power plan and only changed the Maximum Processor State setting.) 

There is good news and significant bad news.

The good news is that setting max CPU at anything other than 100% - even 99% - makes the computer essentially silent even during a CPU intensive task such as encoding.

The bad news is the significant impact on performance!

I had thought that if you set the Maximum CPU State to 90% that you would lose something close to 10% of performance - so a 99% setting should hardly make any difference to performance. In practice the difference is much, much greater.

Setting max CPU usage to 99% does not reduce performance by 1% - in my tests the difference is around 30%. The following are my test results when ripping a 2 minute segment of a bluray

It is interesting to see that even reducing the maximum state by 1% to 99% cuts the power usage of the CPU almost by half - from 96w to around 51w. (These figures are measured using CPU IDs HW Monitor -and the figures are constantly going up and down so I am eyeballing an average.) So it is not surprising that even at 99% the system is essentially silent as it is using so much less power and generating much less heat (CPU temp is 65C vs 85C at 100%) so much less cooling is required.

These tests are repeatable - I ran the 100% test twice and it took exactly 60 seconds each time.

In practice 99% and 98% seem to give the same performance - the encoding tool only reports time taken to the second so these two runs probably took the same amount of time.

It would be interesting to see if anyone else who has reduced the max CPU state has seen any reduction in performance on CPU intensive tasks - I assume that you would only see a drop in performance with high CPU usage applications where you can see the impact of reducing the CPU power (e.g. gaming if you monitor frame rates - or encoding if you monitor frames per sec) and you wont notice any difference while web surfing or using MS Office etc.

Overall this makes me think that using this setting isn't really acceptable for me - the performance cost is too high.

Excellent answer Soil85!

I did some further testing and got the following results.

Any setting of at least 3900 mhz seems to have no impact on performance - at least in this particular test. I assume that something else is the bottleneck in this test once the CPU speed is 4000 or above e.g. memory speed. Alternatively the change in performance above 3900 is less than 1 second.

Note that the above values are specific to this 1 minute test. I will repeat the test for ripping a whole bluray and report on the performance, maximum temps and maximum power usage.

Each setting progressively reduces the noise levels under load - at 3600 the machine was pretty quiet.

I suggest that people experiment themselves with the values above and choose whatever mix of performance and noise suits them.

I ran a test ripping a whole movie with the Max CPU frequency unlimited and set to 3900mhz. The two took almost the same amount of time - around 1h 28 min. So that would indicate that a setting of 3900 really does not impact performance.

With the longer test, when the CPU speed was unlimited the CPU temperature went up higher than in the 1 minute test. The maximum temperature was 93C and the maximum power was 101 watts.

(That is 8C and 6 watts higher than the short duration test.)

With the 3900 setting the maximum temp during the longer test was 83C and the maximum CPU power was 89 watts. (3C and 3 watts higher than the short duration test.)

I am still considering an improved cooler to run the CPU at lower temperatures - even if it wont really improve performance. It is a challenge to see if I can get one to fit and work now. :-)