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Adding more molex connectors for fans, puzzled!

Last response: in Components
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September 24, 2012 9:34:52 PM

APOLOGIES IF THIS IS IN THE WRONG SECTION!!!!
good evening, i have been self learning all about "pc building", im not a hardcore gamer but i like to have a powerful system at hand when needed, to me my computer seems fantastic but i would like to keep it running as cool as possible and i now realise i definently should have case fans, my pc is probably nothing special to anyone here but to me it does the job well

first off i will give you a spec
CPU: AMD FX(tm)-4100 QUAD-CORE 3.60ghz
GPU: Asus GTX550TI
PSU: Corsair CX600 V2
MOBO: ASUS M5A 78L-M LX V2
RAM - 2 X PATRIOT 4GB 1333MHZ PC3-10600

i dont know much about overclocking so the system is not tweeked

i bought a case fan for the back as i noticed i have a 3 pin slot "CHA FAN" for chassis fan im assuming so thats great i can plug and play that, my main question is this, im going to buy a front intake fan but i have no more 3 pin slots on the MOBO so i will need to use MOLEX, i have an LED button on the case and its powered from the molex, its only 2 wires and im thinking would it be safe to power a front fan and this led if i attach a splitter, i dont want the PSU kicking out too much power, i blew my old psu (cheap psu that came with the pc when i had it built), im hoping once the fans are fitted it will bring down the temp of my GPU and once i buy a better cpu heatsink my system should be running fairly well

thanks
a b ) Power supply
September 24, 2012 10:50:54 PM

You can add a molex splitter or even a 3-pin splitter with no issues.

Keep in mind that most splitters configure the two fans so that one "talks" to the motherboard and the other is just along for the ride.

Either way, your power supply can handle it.
a b ) Power supply
September 24, 2012 10:57:30 PM

A front fan is unlikely to make a serious dent in the temperature of a video card.

The thing that usually makes the biggest dent in temperatures is the side fan in low numbers of fan setups.

If you have a choice to mount the new fan on the front or on the side, go for the side.

As for the MOLEX connector... MOLEX cables have 12v (usually yellow), 2x ground (usually black), and then a 5v (usually red). Each of those lines can have a pretty large number of amps in them. You could probably get 150w or more off the MOLEX without blowing the PSU if you tried (assuming a high quality PSU).

A case fan doesn't need a whole lot of juice to run. You can get them to run on just 12v x 1a = 12w. Using pulsing (changing which is sending power between the 12v and 5v every split second) you can get some fans to run on just 7w (they will spin more slowly this way). The more juice the faster it goes, to a point, and vice versa.

Basically, you could connect many fans to the same MOLEX line without even seriously denting its ability to power the fans. You couldn't put enough fans in a PC to overload the MOLEX connector.

The problem is just connecting them all. Luckily some fans come with special MOLEX connectors that are easy to daisy chain with fan wires that connect to the middle of a MOLEX connector that has one male end and one female end.

It works the same way if you split one MOLEX connector to two MOLEX connectors with a special adapter. As long as the PSU is strong enough to handle the load then nothing special will happen to the PC. The PC will just shrug it off and keep going.
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