[SOLVED] Dell Inspiron 15-3521: Constant high fan speed, CPU running very cool

[lachumproyale]

I have a Dell Inspiron 15-3521 that I got from someone since it was busted up - the screen was cracked and the fan was kinda grinding. SO I replaced the screen and the fan, wiped it, and installed Windows 7 on it (it was running 8 before which I hate). It seems ok so far but the fan runs at full speed ALL THE TIME. the CPU is cool as hell, running at like 28 degrees celsius. I even put it on top of a freezy pack and had it go down to like 24, still no change in the fan speed. I got rid of any yellow triangles in device manager, made sure the BIOS is the most recent version (A14 - also there are no fan options in the BIOS, I looked). I also installed SpeedFan and CPUID HWMonitor, and neither of them "see" a fan, and the former won't allow me to add a fan control in the configure menu.

Long story short I have no idea why the hell the fan will only run at full speed. On startup it kinda ramps up to full speed and then just stays there. It's loud, and I want to use it for recording music so it's starting to really drive me nuts. It's actually COLD. I have no idea how to proceed cause I can't even see how fast it's spinning (Judging by the speeds I hear it at when I ran the diagnostic from BIOS, it's running at over 5000 RPM)

Any ideas?

 

[lachumproyale]

So... Kinda stumbled into the solution accidentally, still not sure how I got to this screen, or if it's repeatable

I was in the BIOS and I saved and exited, and restarted the BIOS (F2) immediately again coming out of that screen. I was prompted to select the Model, something I hadn't seen previously. I selected that and when I restarted, the fan runs normally!

weird but solved