PWM fan splitter safe to use?

rdjg22

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Oct 9, 2013
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I have an H97n-Wifi that only has one System fan header in a Bitfenix Phenom. Wondering if it would be safe to use a silverstone fan splitter to run two 120mm fans off the one header. I've read some people say it's fine and others warn not to.
 
Don't know if you're still looking for an answer to this, but if you are, one fan per header is the ideal. The two basic reasons for this are to ensure that the header power capacity is not overloaded and so that RPM feedback is accurate.

There are two kinds of PWM splitters: powered and unpowered. If it's powered, it'll have one cable to draw power direct from the PSU, one master 4-pin connector , and one or more 4-pin connectors that have three wires (positive, ground, and PWM). If that's the kind you have, then you can connect as many fans as you have connectors without having to worry about the header power capacity. Need to make sure that the header is an actual PWM header though, otherwise all the fans will run at max all the time.
If it's unpowered, say for two fans, one fan connector will have four wires (the master) and the other will have three (again, positive, ground, and PWM). The header (and by extension, mobo) will only receive RPM data from the fan hooked to the master connector. With this setup, you need to check the power requirements for each fan. The cumulative draw at max needs to be less than 1A/12W. You also don't need the header to be a PWM header - if the mobo allows voltage control for the header, you'll still be able to control both fans.