What's needed to increase a molex output to 13 ~ 13.5v?

Are you wanting to increase the speed of the pump itself or of the fans? Either way, modifying anything like that in your PC could have some serious consequences for your PSU or system as a whole.

You probably could with some capacitors, but increasing the voltage increases the RPM, but it also decreases the current, which in turn decreases the torque on the motor. I don't think you'd really see much difference in pumping speed, but if you don't care about burning up the motor I can make up a quick schematic for what you need haha.

throwing capacitors at it won't increase voltage - and FYI, all dc brushless motors are microprocessor controlled - more voltage does not guarantee more RPMs.

i'm willing to bet their electronics inside also regulate the voltage. so you could pump in 14v but still would spin at the same rpm.

You do realize that if you killed the pump while your computer was running, your processor would be in some SERIOUS trouble as it would get insanely hot, very, VERY, fast. That said, there are already enough H80/H100 pumps that dont even get to their rated speed because of the Corsair pump rattling issue. If it were me, I'd just leave it alone, if it ain't broke, don't fix it.

Come on guys, give the man a break. If he wants to fry the H100 who are we to judge? It's in a way like overclocking the cooler...

Back on topic, the +12V rail is DC and you'd need say 14V of DC - the thing is one can't simply turn DC voltage from one level to the other like you can with AC, on AC a simple transformer suffices. On DC you need something more complex like a buck/boost or a DC/DC which can be expensive and/or complicated if you wanna build it yourself. There could be ICs that do exactly what you want, but you'd still have to filter the 14V side. This is the clean and proper way to do it, but it's also complicated and/or expensive.

The easier way as I see it is to hack the motherboard ATX connector. Here are some examples of voltages that one can take from a regular MOLEX HDD connector: +12V between +12V and GND, +7V between +12 and +5V (12-5), etc.
Here you can find the pinout for the ATX connector, it is the only one that has negative voltages:
http://pinouts.ru/Power/atxpower_pinout.shtml
The idea is that for more than +12V you'd need to power between the +12V rail and minus-something so that for example H100voltage=+12V-(-5) ==17V. There's not much granularity, ATX plugs only have -5V and -12V and they can't supply much current anyway. 13.5 is impossible, you can have 17V between +12 and -5 or maybe +24V between + and -12V. However keep this in mind: -something rails aren't meant to power much of anything, so it's likely they won't be able to even if you hardwire them; also you need to hack the ATX plug or cut for example the -5V wire to insert a "Y" - so if you could short your PSU and fry everything.

Well anyway you tackle it, keep us posted. It could be interesting to see if something works

What you need is essentially a DC-DC Boost converter. I wont go into to much detail here but if you are confident in your soldering skills and know how to do basic electronics then thees links should point you in the right direction if you want to build your own

http://pointless.info/boost_converter
http://reibot.org/2011/08/07/intro-to-boost-converter/

Just remember the multimeter is your friend and always always test and dile in the thees things on stuff you can afford to fry. Best of luck
Edited by Bit_reaper - 8/13/12 at 2:03am

easy, you can do it for bout $7-$9.

Get a MC34063A chip and wire it up like this:



Ct = 300 pF
Rsc = 0.3 Ohm
Lmin (you can use a higher one) = 70 uH
Co = 330 uF
R = 180 Ohm
R1 = 1k
R2 = 10k

Vin is +12, the Vout will be 13.5V to 13.75V and a max current of 1.1A. It will have a max ripple of about 100mV at 20kHz.

PS: you're gonna need resistors rated for at 1W on R1 and R2 and please get at least the 1% ones. Use a 1N5818 for the schottkey diode.

EDIT: I forgot to label the input capacitor, use 100uH there.
Edited by Dream Killer - 8/13/12 at 2:37am