how does cpu fan determine fan speed.

[dc5]

cpu: 3.0ghz prescott
ram: 512mb ddr4000 sdram

whenever i play games, the cpu starts to heat up quickly. i currently have the stock fan. is the fan suppose to spin according to the cpu temps. eg. higher temp, higher cpu fan rpm and vice versa. right now, the cpu fan stays at a constant speed, even when the temps start to increase.

the reason i ask is, because i bought the antec sonata today. when i had my old case, the cpu fan was dynamic. with the sonata, the cpu fan seems to be constant. could cpu fan rpm be determined by a temp sensor on the motherboard (not cpu)?

from motherboard monitor, the cpu fan goes to 2600-2750 range. is that considered dynamic or constant?

 

[Matthias99]

Originally posted by: dc5
cpu: 3.0ghz prescott
ram: 512mb ddr4000 sdram

whenever i play games, the cpu starts to heat up quickly. i currently have the stock fan. is the fan suppose to spin according to the cpu temps. eg. higher temp, higher cpu fan rpm and vice versa. right now, the cpu fan stays at a constant speed, even when the temps start to increase.

the reason i ask is, because i bought the antec sonata today. when i had my old case, the cpu fan was dynamic. with the sonata, the cpu fan seems to be constant. could cpu fan rpm be determined by a temp sensor on the motherboard (not cpu)?

Fan speed is determined by the amount of power supplied to it. Some motherboards or power supplies (and some heatsinks) adjust the speed dynamically. Others keep it constant.

Is the CPU fan plugged into the motherboard? If so, the speed should be controlled by the motherboard. If you plugged it into the PSU, it's controlled by the PSU (if it offers dynamic fan control, there's usually a 'fan-only' header to use for that).

 

[DaveSimmons]

IIRC, the retail HSF has its own self-contained but crude thermal control, doesn't use the mobo or power supply.

Some motherboards like Asus' also have BIOS control of the fan that offers more dynamic control of the fan, slowing it down much more than the HSF does on its own when loads are light.

If you're concerned or want more quiet, get a Zalman 70000-mumble-alCU HSF for $30-40 and enjoy the near slience and lower temps.

 

[DaveSimmons]

Is the CPU fan plugged into the motherboard? If so, the speed should be controlled by the motherboard. If you plugged it into the PSU, it's controlled by the PSU (if it offers dynamic fan control, there's usually a 'fan-only' header to use for that).

but that is for a case fan, so don't use it for your CPU!

 

[dc5]

but my main concern is, when i had my old case, the cpu fan was dynamic. with the sonata, my cpu fan stays at constant.

p.s. what should i set my prescott 3.0e temp to shutdown at? 60/70/80/90 C.