Questions About Sys Fan Header and 140mm Fans


Limp Gawd
Sep 9, 2010
Hi. I have a Gigabyte Motherboard and an NZXT Lexa S case. Here are links to my hardware, they are the exact models that I am linking you to below.

Gigabyte P55M-UD2


I have multiple questions so I will number them.

1) My case came with four fans but I plan on adding another, for a total of five. I would like to connect these fans to the motherboards sys_fan header so that I can change the fan speeds according to temperature. How do I hook up my soon to be five case fans with their 3-pin molex connectors to the single 4-pin sys_fan header?

2) I want to purchase two 140mm fans for the top exhaust spaces provided in my case. These fans will be in a horizontal orientation and therefore cannot have a sleeve bearing. Please recomend me some affordable fans that I can use. I would prefer the fans to be black.


Supreme [H]ardness
Aug 25, 2006
most mother board fan headers are rated for 1 Amp (12 watts) I would watch your load as 5 fans could be getting close to that. The fans should be marked for current draw or wattage. Also check you manual it might give the max load and if so thats what you should go by. I would not load the header more than about 80% of rating so .8A (9.6 Watts) is about where I would stop with the fans if no other information about the header rating was availalbe.

You can use splitters or splice red to red etc. black to black etc. and just plug the 3 pin into the 4 pin header. Use only one yellow wire from a "master" fan you randomly pick. Do not connect the other yellow (RPM) wires.

Make sure your motherboard has the bios option to run the sys fan header under "voltage control" or "legacy" mode.

Someone else will have to recommend the 140mm fans,


Fully [H]
May 15, 2010
I have that very case (I needed one with a door for various reasons), and just be careful with wiring for the 8pin plug on the motherboard with 140mm fans up there. With an ATX motherboard theres next to no room up there. Just something to consider.