Unsolved
This post is more than 5 years old
5 Posts
0
138452
Optiplex 390 cpu fan run at full speed.
Hi everyone. I already opened a discussion some time ago about a similar problem, but i'm back here again.
Let's start from the beginning...
I bought that pc refurbished in 2013, it came with an i3 2120. After that i added a 430w psu and a r9 270x and nothing went wrong. The next upgrade was an i5 2550k with an arctic freezer pro 7, and here the serious problem appared. The fan of the new cpu cooler was running at full speed all time and it was showing a cpu fan alert at startup. I partially solved using speedfan, but today i wanted to completely solve the problem, so i mounted back the i3 with the stock cooler to monitor the signals of the fan and then recreate it with arduino. But something unexpected happened... The stock fan had exactly the same problem of the arctic exept the fan alert not showing up anymore. At this point I tried the system diagnostic and it told me that is missing the intruder switch cable. After further research i discovered that this is not related to fan in any way, but i wanted to tell you anyway.
At this point i really don't know what to do, so i'm asking if someone knows some way to solve it.
Thanks for reading and let me know :)
beamermt79
4 Operator
4 Operator
•
2.3K Posts
0
January 9th, 2016 14:00
So a couple of things come to mind. I double checked the chipset and it looks like the cpu is compatable however the BIOS may not be. Dell only confirms a select group of CPUs for each model and if your new CPU isn't on the list, the computer may not be able to handle it, especially since its a K variant that is designed for overclocking. The 2nd thing that I wonder is the thermal sensors. Were they damaged or unplugged at all? I'm not sure about the Optiplex but some computers have sensors that can be unplugged on accident.
Dereek69
5 Posts
0
January 9th, 2016 18:00
Thanks for the answer.
I know that the i5 2550k is not directly supported by the bios, but it never gave me a single problem.And I was also using the i3 in this test, so the incompatibility of the cpu is't the problem.
Speaking of the thermal sensors i don't know if it can be unplugged on this model, but speedfan and hwmonitor can clearly read the cpu temps.
Another strange problem i found is that i cannot output a "fluid" pwm signal for the fan. If i set the pwm out to anything from 0 to 35% there is no output signal and the fan run at 850rpm, after 40% and before 65% the fan is at 2200rpm and over 70% the fan run at 3350rpm. So it has only 3 speed steps, and this makes me unable to simulate the signal
beamermt79
4 Operator
4 Operator
•
2.3K Posts
0
January 14th, 2016 10:00
Hmmm, never played with that. It could have a very tight thermal profile in the BIOS. My response will bump up this thread so maybe someone else has an answer.