Question CPU fan not spinning up stays at the same speed

[daudkhota]

So I have an i5-2500k in a motherboard that is made by lenovo I'm using the stock cooler when I take out this 5 pin connector its green and restart the pc the fan goes to max speed. However when I plug this 5 pin green cable back in my CPU fan stays at the same speed and doesn't go faster temps increase to stupid number like 70 degrees but when the cable is not plugged in my pc sounds like an aeroplane but my degrees are very good at 50-55 degrees I would take a picture but I don't know how to ;(

 

[CountMike]

So I have an i5-2500k in a motherboard that is made by lenovo I'm using the stock cooler when I take out this 5 pin connector its green and restart the pc the fan goes to max speed. However when I plug this 5 pin green cable back in my CPU fan stays at the same speed and doesn't go faster temps increase to stupid number like 70 degrees but when the cable is not plugged in my pc sounds like an aeroplane but my degrees are very good at 50-55 degrees I would take a picture but I don't know how to ;(

Check in BIOS, must be some adjustments for fan speed.

 

[daudkhota]

My bios literally doesn't do anything with fan speeds in fact it doesn't even have any options for fan speeds my mobo is an Lenovo thinkcentre m91-p

 

[Joakim Agren]

So I have an i5-2500k in a motherboard that is made by lenovo I'm using the stock cooler when I take out this 5 pin connector its green and restart the pc the fan goes to max speed. However when I plug this 5 pin green cable back in my CPU fan stays at the same speed and doesn't go faster temps increase to stupid number like 70 degrees but when the cable is not plugged in my pc sounds like an aeroplane but my degrees are very good at 50-55 degrees I would take a picture but I don't know how to ;(

That cable you removed is it a 3 wire cable one being green in color? Does that green cable have a thing that looks like this mounted on it:

Sometimes the resistor will be hidden behind sleeving like this:

This resistor will reduce the 12 Volt to either 7 Volt or 5 Volt so that the fan will run at reduced and quiet speeds. Zalman used to include these with their coolers. 70 degrees Celsius is not a particularly high temperature if you mean that is the temperature under heavy load so I would just leave it in there. If it is idle temperature then something is wrong, perhaps you need to clean the cooler? Is it dusty?