allardjd 1,853 Posted December 7, 2009 Report Share Posted December 7, 2009 Does anyone have any insight into how fan speed is typically controlled in PCs? My 2+ Year old PC always starts with the fan in high speed, just for about two seconds, then shifts down to a lower (read quieter) speed. For about a week now, it's starting in high speed and remaining there. It is not a heat issue because this is on a cold start after the PC has been off overnight. Everything in the PC should be at ambient temperature at that point. There are three fans, a big case fan in front, a GPU fan and a power supply fan. I'm pretty sure it's the big case fan that is the one that is behaving differently over the past few days and is making all the racket. The PC is not Uncle Martin clean, but I've cleaned and checked it and that doesn't appear to be the issue unless there's some localized problem that I'm missing. There wouldn't be something as archaic as an air-vane controlling that, would there? Some insight into what/how the fan speed is controlled might help me understand this. Thanks... John Link to post Share on other sites
simi_av8r 0 Posted December 7, 2009 Report Share Posted December 7, 2009 Does anyone have any insight into how fan speed is typically controlled in PCs?My 2+ Year old PC always starts with the fan in high speed, just for about two seconds, then shifts down to a lower (read quieter) speed...... Some insight into what/how the fan speed is controlled might help me understand this./quote] Well, as it happens, i had this problem also not so long ago...but turns out my issue was that of cleaning (or inherent lack of for the past 18=months plus!!) Anyway, case and CPU fans are, typically, controlled by on-chip temperature sensors and connected close to or on the CPU socket. The CPU sensor is, yep you guessed it, inbuilt on the CPU and its data is fed to the mobo via the CPU socket. The GPU fan is very much the same, and it's fan will be directly connected to the GPU board and will throttle up/down accordingly based on GPUs core temperature. Case fans, on the other hand are connected, usually, to the main board via a small 2 or 3 pin cable and, in some cases, a separate 5-pin molex power cable. The small 2/3-pin cable provides power (additional power provided by the 5-pin molex if present) to the the fan and is controlled by the main board temperature sensors. In all cases, if the sensors detect a rise in ambient temperature or a fall in air flow inside the case, then the fan speed will increase and decrease when a 'safe' temperature is attained. If you really want to go full pelt and see what speed and/or temperature the sensors are reading, then a little application called SpeedFan can help. I've posted a screenshot of its interface below to show what it reads, click it to go to the download page. well, i hope that helps John, if not sling me in the stocks and throw sponges at me! Simi Link to post Share on other sites
allardjd 1,853 Posted December 7, 2009 Author Report Share Posted December 7, 2009 Thanks, Simi. I'll check that out. This thing is showing it's age and it may be time to start thinking of getting a new one into the budget. If I sling any sponges your way I'll be sure they are soaked in beer. John Link to post Share on other sites
simi_av8r 0 Posted December 7, 2009 Report Share Posted December 7, 2009 This thing is showing it's age and it may be time to start thinking of getting a new one into the budget. your's is a wee nipper compared to my archaic machine... i'm still running a custom build originally made way back in 2001, and not upgraded since 2003, and even then i only added 2x 512MB sticks of RAM! Link to post Share on other sites
allardjd 1,853 Posted December 7, 2009 Author Report Share Posted December 7, 2009 ...my archaic machine... i'm still running a custom build originally made way back in 2001... Ah, but you're in the UK. You folks have such a rich history you don't consider anything old unless it was built before the 1600s. John Link to post Share on other sites
stu7708 244 Posted December 8, 2009 Report Share Posted December 8, 2009 Ah, but you're in the UK. You folks have such a rich history you don't consider anything old unless it was built before the 1600s. John To quote Eddie Izzard from a show in the states... "I'm from europe, where history comes from" :great: 18 months old shouldn't be a problem, my home desktop is about the same age. Depending on what hardware you have in it, upgrading some parts of it should keep it alive and kicking for another 18 months or so... I'll most likely look into an upgrade of my processor and GFX-card, and possibly the PSU. If I can only sort out the troubles I have on starting the b****y thing. Every now and then it stops dead in it's tracks during the boot up POST. That said, I do feel that electronics did live longer if you back up four or five years. But they where more expensive too... Link to post Share on other sites
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