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242
6420XFR
Recently acquired this XFR 6420. It ran hot compared to what I'm used to. Bios diagnostics results log showed 3 "thermal events" and 1 "fan stopped" all dated 3 months before I got it. I replaced the pads (1.5mm) and CPU paste which helped quite a bit to keep it from reaching high temp as quickly.
The fan test in BIOS shows "target 2500/actual 3500" and "target 4900/actual 3900" all within specs of 40 percent variance. But this one seems to only start when the CPU reaches 92c and totally stops about 70c. Never throttles or runs more or less than about 3500rpms. (guessing by sound)
Is that normal for this model, or could there be an issue in the motherboard or possibly the fan signal-to-board?
Bios updated A24 and everything seems to run great, just concerned about the longevity. Thanks.
ejn63
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July 12th, 2022 16:00
It could be a number of things, but start with a run of the Dell diagnostics, which will test the operation of the fans.
You may also want to examine the fans to make sure they're OEM Dell and that they have not been replaced with non-OEM fans at some point -- there should be a Dell part number on the fan assembly.
RWC 3
8 Posts
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July 12th, 2022 17:00
I've run the diagnostics which says all tests pass, though on the fan test portion it shows a target speed of 2500 - detected speed 2987. 2nd portion of test, target speed 4900 - detected speed 4057. The detected speed detected varies about 100 rpms on each test after doing several.
I had it out re-pasting the heat sink and the fan looked about the same as the rest of the interior, but I don't recall a part number tag. The log showed a "fan stopped" event before I bought it, so it's possible it was replaced with a used fan or an aftermarket not quite totally correct for this model.
Considering that and your advice, I searched and found a new OEM fan. I'll post back with results when it's installed. Thank you.
RWC 3
8 Posts
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July 18th, 2022 15:00
I installed the new OEM fan. The one that it had was OEM as well so that made no difference.
I'm confident I got a good Squeeze on the GPU pad and CU paste. The other spot got a 1.5mm pad that looks barely thick enough, though. I've no idea what it sits on, I'm a novice. Just seems odd they would program the fan to not engage until it's 10c under Tj max of 100c and it kicks off at 80c.
HWinfo program works great for setting fan engagement temps/speeds but it's not an auto start program so has to be set at every boot up.
Overall the machine does well and doesn't heat up until it's working hard but never does cool off after it gets to high temps unless it idles a while. Disabling Cortana and Windows Defender makes it usable with Win10 and with Win7 it does well. Stays around 50-70c @ 75f ambient.
Thanks for the replies.