To give an update. Dell approved the refund and the pc is being returned. I will close this issue (while not being a solution) 
Hey, I have a Dell XPS 8940 with an i9-11900k since April this year (2021). Since the beginning of this month, the PC started to occasionally shut down (now, end of November its almost every 10 minutes). After investigation, I found the temperature was spiking to 100 deg C. I cleaned out the fan and heat sink (not a lot of dust in the relatively new pc) but the issue remained. After many many many tests that I had to perform by dell support (I have premium support with 24h on site repair btw) they came to replace the cooler. This post is mainly to try and understand if I am super unlucky with my repairs, or if this is a design issue (which would mean that I am not going to go for this configuration again) Repair guy 1:Did not seem to be from dell itself, was super friendly - replaced the cooler and fan. Mentioned that there was almost no thermal paste on it. He cleaned out the pc again and the PC was working fine in idle. The temperatures were lower than before (in idle) to 30-40 degrees. However, 1 hour later I got another shutdown and after again performing some tests it seemed that the cpu was heating to 97 deg C again. To save some time, I wanted to do a new stress test using Dell's SupportAssist. However, this time around it did not even manage to pass it. It shuts down immediately after starting the test. Sometimes I am just able to see the flag "Core critical temperature" turn to "yes" in HWInfo before the shutdown. Called Dell again, today they came with a new motherboard. * NOTE *: I have a K processor with a 'larger' cooler. However this repair guy said that I should swap it ASAP as soon as the warranty is over. Repair guy 2:He replaced the motherboard (1+hour work). Googled some BIOS errors because he forgot to transfer the Voltage Regulator heat sink from the old board. Removed the front face of the XPS, but afterwards the power button was not working properly (currently have to press it hard with a finger nail). Also found a plastic bit that was broken of from something, later found out it was from the plastic thing that keeps the GPU bracket in place. Anyway long story short: the thermal issue was not solved and the pc again reaches 100 deg C with thermal shutdowns whenever I start a McAfee scan, run the dell stresstest or even when OneDrive starts a sync. The BIOS is up to date (2.3.0) but the issue also happened on the BIOS that was installed when they replaced the board. But now comes my hard decision that I need some help with. Of course I called dell again (tbh I am quite surprised that I remained so calm on the phone). I asked them to either swap the complete system, send someone to troubleshoot it or a full refund. - The full refund requires permission from a supervisor and may likely not be granted since its already bought in April. If it is granted he can give a discount if I decide to buy a dell again.- He did not recommend the swap as it will take at least 6 weeks- Apparently on-site troubleshooting is not possible, they have to send it to Germany (I am from Belgium) to do so. They said the only issue that can still be is the PSU, which is something they do not replace on site. I like the specs of the pc, apart from its thermal issues. If I google for similar issues, I mainly find issues from people who do not have the "K" processor and thus have the smaller cooler. Is there anyone with the i9-11900k who also have or had a similar overheating issue? I am deciding if I should still go for a replacement/repair of the XPS 8940 with same configuration, or if there is a serious thermal design issue on Dell's part. Some context about the pc:- It is placed in a bracket, there is 2 meter of space in front of the pc, 1 meter on the back without any obstacles and 30 cm underneath.- Room temperatures are colder than in the summer (I did not have the thermal issue in the summer)- Windows 11 (since a few months) , However, I reverted to a windows 10 image of June 2021 to see if that was the issue, but same result- After a hard shutdown due to (what we assume is) the temperature, the PC can not be booted. I have to plug out the cable. Personally I do not feel like the PSU could be the culprit. While it can cause a shutdown, it should not cause temperatures of 100 deg C (I think this is btw the max that can be recorded). This is a picture of the dell stress test running for 30 seconds, 1 second before it caused a shutdown. This is after a fan, cpu cooler and motherboard replacement.[IMAGE]CPU temperatures 1 second before shutdown after cooler, fan and motherboard replacement Thanks,Maxim Van de Wynckel
XPS 8940, i9-11900k overheating