1 CPU header for H20 620 & 2 fans

Steveocee · 21 Nov 2012 at 00:37

Hi all,
My fans are reasonably quiet however I have to have my CPU fans at full bore as I have no real way of controlling them currently.
However I have been looking into using a splitter to run my Kuhler H20 620 and 2 fans push/pull off of them. Is this an OK kind of set up?

I have done a little digging and found my mobo (M4A87TD) has an output of 24 watts (2A)

2 fans use .84w each (taken from random google search of fan)
Kuhler uses 2.6w for pump (only 1 site had this info)

Do those numbers sound right and am I going to be OK using a 1 into 2 way splitter to power both my fans from the piggy back header on the kuhler?

Thanks

Tealc · 21 Nov 2012 at 08:24

0.84W + 0.84W + 2.6W = 4.28W

Add some startup overhead on top and you'd still be fine.

Isn't it better though to use a Molex to 3 pin converter and have the 620 powered off that, then worry how you are going to control the fans, perhaps by PWM or something.

Steveocee · 21 Nov 2012 at 08:40

I wish I could do something like that to be honest. As far as I know, I have 1 connector that goes into the CPU header and then piggybacked off that I have another connector which you connect a fan to.
My plan is to put a piggy back onto that to run both fans from that.

I believe the motherboard header uses voltage control for the fans.

Tealc · 21 Nov 2012 at 09:20

You don't want voltage control on the pump though. That really needs to run at near full speed all the time. The fans, however, should be controllable by bypassing the 620s fan connector and using the actual CPU header, which should controllable by some method.

The best thing to power the pump with would be the PWR or the CHA_FAN1 headers, which'll always be 12v.

I'm not sure if the bog standard Asus Fan expert does actually allow voltage control of 3 pin fans, I do know that for a time many Asus boards lacked the DC voltage control and had to rely on PWM control, at least until Fan expert2 came along anyway.

There's really no need to have the 620s fans running at full pelt when you are sat at idle. If you would like to find out about converting your 3 pin fans to run off 4 pin PWM take a look at my PWM converter thread