Flex 4k overheat

[MintBerry]

Hello. I made a post a long time ago about the Flex 4k overheating, asking if anyone else has the same issue. It's out of warranty so RMA isn't a possibility. Strangely it looks like my post was removed. If I am violating a forum rule, you have my apologies.
My solution is to keep it on top of a HEPA filter where the air blows across it, and that works. However that means if it falls off of the filter I lose TV. Coax cable is stiff and the Flex 4k is so light that it tends to go wherever the coax wants to take it.
I'm thinking I can attach a generic heatsink to the metal plate on the bottom and maybe put a little USB fan on it. Has anyone tried this? Does anyone from SD have any advice? I can't be the only one with an overheating Flex 4k, right?

[nickk]

Hi,

No rule problem, forum threads that are idle for more than 90 days are automatically purged.

Is your 4K in a living space inside your home? Something is wrong if it needs forced air cooling.

I can check a few things - what is the device ID of your HDHomeRun?

[MintBerry]

It is in an air conditioned space and the past 2-3 days it was a little under 70F in there. As of yesterday it had fallen off of the fan and that was causing frame skips and audio dropouts. I thought it was my signal booster but everything checked out and moving the HDHR back onto the fan had it working normally within minutes. In the hotter months I let the house go to 74F sometimes, at that temp the Flex 4k occasionally stops responding entirely until I power cycle it. But, with the forced air cooling it is completely fine. I think I put it back on the fan around 6-7PM EST yesterday (11/28).
Device ID: 10A10E81
Thank you for checking!

[KeithAbbott]

In case you need to stick with your original plan, I am using this fan (https://acinfinity.com/equipment-coolin ... -fan-80mm/) attached to the underside of a non-SiliconDust device with zip ties to secure the two together. The unit is in a cabinet with a frosted glass door, so nobody sees it. It's been working well since 2020, no heatsink required.

[jasonl]

Please go to the HDHomeRun's web page at http://hdhomerun.local/ and click on System Menu then enable Send diagnostic information. Watch TV for at least 10 minutes with cooling and at least 10 without (or longer if needed to see issues), then reply back with the time when each was done, and we will review.

[MintBerry]

12/5/2025 All times EST
5:05PM - 5:20PM actively cooled by HEPA filter. This is how I operate it now.
*** 5:20-5:29 this probably not good data, it was not fully off of the fan.
5:29PM - 5:40PM no fan, room temp 65F. At 5:40pm the plate on the bottom was warm but it does get warmer, given more time.


I didn't have any issues while doing this test. Sometimes the room temp is 75F in the summer. Maybe the test didn't go long enough to have the issues, or maybe 65F is cool enough to not have them.
I really appreciate you all taking a look. Is it possible that a heatsink inside my HDHR is not mounted well? I'm not against taking it apart if instructed.

[jasonl]

Nothing in the logs, but I wouldn't expect there to be if you didn't see any issues. The metal plate on the bottom of the HDHomeRun is the heatsink. If you want to pop it open and check to make sure things are making good contact you can certainly do that; as you noted, it's out of warranty. 65°F vs 75°F shouldn't make any difference. A couple of mine regularly operate in 80°+ ambient in the summer and I don't do anything special, though I will note that they don't sit flat just because they're too light to overcome the stiffness of the coax cable.