Do Molex to 2x 3-pin adapters somehow throttle the fans?

squelchy451

Member
Oct 20, 2010
101
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0
Hi. I have this molex 4 pin to 2x 3-pin adapter that powers two fans from a single 4 pin molex port. When I connect a fan to one of the 3 pin ports, the fan runs really slowly. I have a fan that comes with a 4 pin adapter built into the fan, and when I plug that into the same molex port, the fan runs at full speed.

So does the adapter only supply 50% of the power to each 3-pin port? I don't blame the PSU since it's a Antec TruePower 550W powering a i3-2120, H61 mATX mobo, Radeon 6670, one 2.5" 5K RPM drive, one 3.5" 7.2K RPM drive, a DVD burner, and 3-4 fans.
 

Ayah

Platinum Member
Jan 1, 2006
2,512
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Some adapters supply either 5v or 7v to the fan (instead of 12v) simply by switching the wiring a little (for the quiet enthusiasts). Can you check to make sure that the adapter passes 12v through?