You can do that already just get a 4 Prong PWM Fan-Splitter. Make sure your motherboard lets you control fan speed (heat ranges, percentages, etc...). I think even SuperMicro do to some degree, not as well as my X99 MSI though. Set the "If between x - x range fan speed 10%" then they're silent, and then you can do other tiers (Depending on motherboard) or just set your medium then high (or just high), but beware that's a good way to go from cool to hot a lot, and heat cycles aren't the best for any electronics. If it were me and that was my goal I'd get silent as fans as I could, then monitor them with the LV fan adapters, see if that's all you need... simple, and affective. If not AND heat is an issue I'd get the 3000rpm PWM Noctua fans (I have.) and do a simple fan control tune in BIOS and call it good once you get within range, you can always tweak for sound / temp later if it's within spec
but with 3k RPM you really shouldn't worry about over heating either which is a nice feature!!
Obviously you're limited to the probes/sensors used for PWM options, so I can see another option (like a fan controller) being something to check out.
I wasn't planning to use the results for any automated response but rather graphing and viewing the data visually to get an idea how heat builds over the day, and if it ever cools while I'm away/breaking.
I do have other plans for one of those "mini systems" that I can build, and then monitor a # ( 2-3 likely ) of probes that will work with a relay for the on/off exhaust vent fans for server room based on inside & outside temp differentials. I think my goal will be to do outside temp, server room temp, office temp and then write a couple super basic algorithms to open/close vents/fans based on temps via relays. I figure it may be nice to cool my office when the server room cools as long as I'm not blowing heat into the office instead of out the exhaust vents. I'm not sure how much the new
raspberry pi can handle but it sounds like I can do all that with 1 device now, not 100% yet. I also have humidity sensors/relays, and temp sensor controls planned (all digital) for "setting" a temp too, as there will be a 13K BTU cooler in the room to keep it within spec, technically I could put a dehumidifier in there but I see 0 reason with our humidity on the west coast, and monitoring it closely over the last 5 years w/heat & without, etc...
Too bad the server room temp & humidity isn't conducive to cigars... could move my cigar collection from a large fridge into a real "walk in" humidor.... LOL Somehow I don't think the wife will let me use her side of the new 'storage', errr server room
(Separated by doors of course,
)