Inspiron 5680 Desktop CPU Fan running at full speed at startup

Hi,

Are the latest BIOS version and chipset drivers installed?

Not sure on this one but have you checked that the service mode jumper on JMP1 pins 1 & 2 is set to default i.e. no jumper? JMP1 pins 3 & 4 should be the only pins with a jumper on them, 1 & 2 and 5 & 6 are open

Is the RTC battery OK?

It’s normal for it to happen within the first few seconds on the Dell desktops - most people don’t notice because they don’t know it happens. If it stays like that for more then 5-10 seconds and it’s a no boot situation, it’s usually a RAM or power supply issue. The startup RPM is not as aggressive as the Core 2 generation was, but it still happens and you can tell if you know what to listen for during POST.

The cheap common fault I’ve seen when it boots is someone did a fan swap and it provides insufficient PWM data since the machine is somewhat specific about what data it expects. When it isn’t providing RPM data, the fans assume there’s an issue and run them at 100% speed all the time, along with throwing a BIOS boot warning. If you see a boot error, start with the fan in question with these machines. CPU is 4-pin and rear fan is 3-pin and it needs to provide RPM data - stick to the Delta fans Dell uses as those provide the correct data.

For non-booting machines, the first thing I do is inspect the power supply for an issue (connection or physical problem) and replace it if it’s not due to something like the 4 pin 12V ATX/P4 power connector (P4=first machines to require it). That solves it most of the time with non-booting systems. NOTE: You have a huge issue - 2 different power supplies based on the factory CPU spec! Lower spec machines (i3/i5) use the stupid nonstandard supply like Lenovo, but the high end (i7) machines use the ATX 24-pin. PRAY IT HAS THE NORMAL ATX PART OR YOU NEED TO USE THE DELL PART.

If the power supply looks fine/non-standard unit, start with the RAM - that’s the second common cause for the full speed fan issue with a no boot condition. If you have 2 modules, removing one will usually work unless both are bad. When you replace it, don’t mix the good OEM modules with new retail ones - replace it as a matched set. Dell boards aren’t picky, but for normal users it just creates avoidable problems.

If none of those fix it, your motherboard is bad.

I had same problem and fixed, Although it is true that its normal for pc fans to start up at full speed on startup its strange when they dont at first but after an upgrade they run at full speed and stay at full speed

I upgraded my gtx graphics card bought a 3060ti...needed the double 8pin wires from the psu but the back of my pc was a mess so i decided to re wire everything neatly...when i hooked everything bck up i noticed my fans would run at full speed on startup which never did and stay at full speed..took the gpu and placed the old one bck to check if it was the gpu, checked bios to see fan speed settings they were set to standard...checked asus crate app to see the fan setting and was also at standard speed...the asus crate app shows each individual fan current rpm and gives you the header name, cpu fan, chasis fan 1, chasis fan 2 and so on and i noticed that the water pump fan was reading rpms, i dont have water cooled system, i looked online to see the location of water pump fan on asus z590-e motherboard switched to a regular chasis fan connector and fixed the problem now my fans run at normal speed set by the heat motherboard & cpu sensors on startup

I know this is three years late but I had the same problem and I thought I would let anyone in the future know how I solved the problem with the CPU fan. My new motherboard did the exact same thing until I noticed that the new board had a two pin jumper attached to CFSEL 1. The original board did not have it. After I removed the jumper everything worked perfectly.