eg: if my cpu is relatively cool, it runs at 2000 rpm and speedfan says 100%. so i though, ok it cant go any higher. Then just 2 hrs later after some gaming the fan was at 2500 -_-
@ I: your right about not knowing what its running at...should have mentioned that before. Any who my cpu is a e6600 and its ideling at around 47-49 degrees C. After playing a game like rainbow six vegas it goes to about 58 ish, and at 100% load its around 65-67.
So what is your goal exactly? You don't want to reduce fan speed at load with it already at 65-67, in this case it would seem you need a better heatsink (presuming the present one is properly installed, making good contact with CPU & not too much thermal compound) or maybe better case airflow.
2000-2500 isn't very high RPM considering your temps, anyone would like to just make a fan quieter but then have to have some thermal margin to whittle away first as the fan speed drops.
My mobo is a asrock 775 dual vsta.
as for my competence at tacking add-on circuits to my PCs.. uhhh...i have none would be the right answer. If I can avoid it I would also rather not spend. But I may just get some new thermal paste and try that, cause im not too convinced about the stock fans thermal paste currently on it. It just doesnt seem to be spread right.
uhhh...what else do you wanna know??
Unless you are McGyver and have some string, glue, and a fish hook, I think it will take a dollar or two at least.
The cheapest option to simply reduce the fan speed would be to solder in a 1W resistor (about 20 cents), maybe 68-100 Ohm on the V+ power lead, cover that with heatshrink tubing (about 5 cents worth but you can't buy a 5 cent piece instead of a few feet at a time, like $1 worth), so that's $1.20 or so plus shipping at a few more $.
You don't have the thermal margins to do it though, reducing fan speed by any method will make it run a little (Or a lot, depending on amount of RPM reduction) hotter, so the motherboard adjusts the fan to a higher RPM to comensate, it could practically negate the mod you do because it will just fight against the mod to keep trying to ramp up the fan speed to get the CPU to the temp set (In the bios?), until the fan is at highest possible RPM (per the fan model) then the CPU just gets hotter, with it already being at hot as it should get.
FIgure out which area of your system cooling is the weakest and combat that first, I recommend getting your full load temp down at least to 55C or lower before thinking about reducing the fan speed. Note that if you get that temp down, the motherboard fan controller may reduce the fan speed automatically (some at least) so you may not even need further mods to get close enough to your goal.