Cooling CPU power regulation components - crazy mod idea inside.
 

I have an abit IC7 which I wish to do a mod on that would make it easier for me to put a waterblock on the MOSFETs.

http://www.abit-usa.com/images/products/IC7-lg.jpg

As you can see, the mosfets are to the left of the CPU bracket in the picture, but the caps and coils stick up and in the way of the actual fets.

My proposed mod is to desolder the caps and coils, and reattach them to the back of the motherboard (in the proper polarity, of course). I've got clearence to do this because the area behind my CPU socket is cut out of the mobo tray to facilitate waterblock mount changes.

Physically, it WILL fit. However, since there will be zero air movement back there, do I have to worry about killing the caps or inductors?

Also, the regulator on this board is 4-phase, indicated by 4 sets of coils (there is one hiding towards teh ram slots that I won't put on the back, as it doesn't interfere)... each phase has a coil, 2 caps, and 2 transistors as the largest components.

the 2 transistors are not the same size, one is large (looks about the same size as a TO-220, but surface mounted) and the other is small (not TO-92 small, but smaller). the clearest part of the image for seeing this is directly above the PS/2 mouse/keyboard ports.

the transistors are not the same height :( it would make block construction EASY if I only had to cool the larger FET. What do the smaller ones do?

I was just thinking what if you use a copper block that would extend above the Caps and coils. then run a waterblock above it.
The extra 1" of coper would affect the cooling somewhat but it should still help...
Also would be cost effective compared to a screw up and having to replace the entire board.

Hum... went through the manual and several reviews; nothing.

You got part #'s for the FETs?

I can get them - I'll post back in a bit.

I'm out in 10 minutes, back Sunday morning; I'll have plenty of time then to research it.

Crazy, but it could work. You considered a waterblock for the backside of your board? The motherboard plays more of a role in disipating the fet's heat than the plastic heatspreaders on the top. There is a thread somewhere in here about mofset blocks.

I've considered doing both and may go forward... at this point I'm just checking options.

The "big" drivers are Phillips PHB108 (thanks to Brians256 - he was google's result for PHB108 MOSFET).

The little guys are labelled:
O9NE0LA (or maybe D9NEOLA)... very hard to tell
and 1313A.

ive seen guys resodler stuff on teh backsides of boards. just, as you mentioned, make sure hte polarity is correct and ur good to go..

Well if you water cool the voltage regulators on the top-side there will be less heat to get around to those caps....right ;)

My $0.02

CFF

Actually...what does the back look like right now? I found cooling the back-side was more effective anyways.

If I had to start over with a new motherboard I'd consider cooling just the back-side and see how that went first. Then if that was insufficient then I would look more into cooling the top-side as well.

CFF

I would just move them to the top of the board by using extension wires, the length of their connections, if kept within the reasonable of course, would not inhibit their function at all.
That would leave them with pleanty of airflow, and if you wish their position would make it easy to extend a bit of copper from the block to cool them.

Cptn Foo Foo has a point: the part of the MOSFET that warms up, is the metal backing, not the plastic part of the package. As counter-intuitive as it might sound, even with the motherboard between the cooler and the hot side of the MOSFET, it seems to cool better that way.

I'll research the MOSFET models you posted, and report results this morning.

The Phillips PHB108 is definitely part of the CPU power regulation:
http://www.semiconductors.philips.co...08NQ03LT_3.pdf
(PDF, 14 pages)
In short, max current is 75 amps, and Rdson is 6 mOhm (what I'd expect)

The 1313A is a mystery. I'd guess it's the On Semi buck controller / driver:
http://www.onsemi.com/site/products/...S51313,00.html

The O9NE0LA / D9NEOLA is also hard to find. Best guess is a simple regulator.
http://www.mouser.com/index.cfm?hand..._pcodeid=58017
(but I'm pretty sure that's wrong)
It could also be a fuse:
http://www.mouser.com/index.cfm?hand..._pcodeid=65000


Last I checked power regulation was either done as 2 or three phases, I'm going to take a shot here and state that you have a 2 phase regulator, and you've got 2 big MOSFETs to cool, that's all.

If the heat plate in the back of the Mosfet will be the one be to cooled, then maybe it can be positioned upwards like the ones inside a PSU? Then it can be h2o cooled just like a transisitor in the PSU?

hrmm... the abit manual doesn't state how many phases the power regulator is... but there are 4 sets of transistors and 4 coils, which makes me think 4 phase.

I've got a backside block planned... just need to track down some mica shim and an appropriate way to mount the block.

You should look into a custom block of some sort... something to match the "footprint" of your mod idea. Do you know any cnc machinists? :dome:

Also, caps and inductors generally do not generate heat.

As long as you carefully remove the caps and inductors with a professional solder removal tool (or solder wick if you must go the cheap route), and note the polarity before removal and reinstallation, there is no reason why your proposal will not work.

Props for and excellent idea.

Before you touch those MOSFETs (i.e. consider de-soldering them) you should find out if they're grounded or live at that point (odds are that they're grounded, but you really have to check)

Think HiPro was the one notorious for moving components around the board... if mounting caps on wire extensions, don't forget to account for added resistance of the wire used...

@gazorp: I do not know any CNC machinists, but I do have access to a guy who can run a bridgeport very well. (At work, sweet...) As far as removing and resoldering components, my formal training is as an electronic engineer, so this is not a challenge. my hakko and solder sucker won't break a sweat.

@bb2k: I'm not going to remove the mosfets, but I was contemplating moving the caps to the back side of the board so that they're not in the way of a flat-bottom'd block for the top side of the board. If I move the inductors and caps, it may cause some small degree of headache on the back side block. I have to go home and stare at things for a while... see what shakes out, ya dig.

@Marci - hipro is the god of the IC7 ;)