Is it necessary to connect the 3-pin header for the H100 onto the motherboard?

TheHeeyyy · #1 05-14-2012, 08:39 PM

Sorry if this looks like a noob question, but I haven't found a clear answer for this question, and I would like a clear answer before purchasing the H100. The computer I am building has a motherboard with two pwm CPU fan connectors, and I have two PWM fans I plan to use with the H100. The H100 has a 3-pin header, which from what I have read appears to provide RPM information for the pump. However, I am not 100% clear if the pump's 3-pin header has to be connected to the motherboard to operate correctly. Can I leave it disconnected and have the pump still work correctly? I believe the answer is yes, since the pump appears to be powered by the 4-pin molex connector, but I would like a response from someone more knowledgeable about the H100.

Thanks

Synthohol · #2 05-14-2012, 10:15 PM

most modern motherboards use a failsafe that will shut down the PC if it does not see a fan signal from the CPU header. 2 ways to circumvent this, turn off fan monitor safety thing in bios (very technical terminology i know...im tired

) or just have another fan plugged into the header which i believe you intend to.
so in essence, no you do not have to plug it in to the best of my knowledge.
i would also suggest maybe you get a splitter for the 2 fans and you can still use the header for the pump? there are splitters out there with only one lead from one connector to go to the speed reporting circuit so the 2nd fan wont misreport the speed.
i know i would feel better that if my pump stopped for whatever reason my PC will shut sown to protect itself.
thermal monitoring with a shut down temp will do this as well.

TheHeeyyy · #3 05-14-2012, 10:38 PM

Quote:

Originally Posted by Synthohol

most modern motherboards use a failsafe that will shut down the PC if it does not see a fan signal from the CPU header. 2 ways to circumvent this, turn off fan monitor safety thing in bios (very technical terminology i know...im tired

) or just have another fan plugged into the header which i believe you intend to.
so in essence, no you do not have to plug it in to the best of my knowledge.
i would also suggest maybe you get a splitter for the 2 fans and you can still use the header for the pump? there are splitters out there with only one lead from one connector to go to the speed reporting circuit so the 2nd fan wont misreport the speed.
i know i would feel better that if my pump stopped for whatever reason my PC will shut sown to protect itself.
thermal monitoring with a shut down temp will do this as well.

Hmm...so connecting the 3-pin pump header would act as an extra safety procaution. If the pump stops working, the motherboard will shut down the computer before the CPU gets damaged. That could be useful. On the other hand, I have heard people say that using a y-cable to connect two fans to one fan connector is not always a good idea, as the added strain placed on it could damage the connector. Anyway, thanks for the info. You've given me options to mull over.

babdi · #4 05-15-2012, 12:09 AM

The 3 pin connector just reads the rpm,nothing more.
You can leave it unplugged if you wish. The pump is driven by 4 pin molex cable

parsec · #5 05-15-2012, 02:24 AM

You can connect that three pin/one wire connector from the H100 to any fan header on your board to monitor the pumps speed. They all won't provide the auto-shutdown that the CPU fan header will, of course.

Modern CPUs will shut themselves off if they overheat, if nothing else shuts off the PC. But the CPU will reach its thermal limit before that happens, whereas the detection of the zero fan speed by the CPU header will shut off the PC before the CPU is toasty hot.

Fan headers generally are rated at 1 Amp/12 Watts maximum each, which is why using a splitter cable could cause a problem with fans that use a lot of power. Your boards manual likely will list the amp rating of the fan headers. Two fans using 0.5 Amp max each would be one Amp total. Many fans use less than 0.5 Amps max, just check the label. That is at full speed, so they use less power at lower speeds. Can we trust the rating? Most fans yes, a very few no, according to tests I read. Some fans use less than their rating at full speed, always a good thing. All the Corsair H-series fans are about 0.20 Amp max, and their new series of fans use even less power.