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Intake behind the motherboard?

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johan851

Insatiably Malcontent, Senior Member
Joined
Jul 24, 2002
Location
Seattle, WA
Does anyone know if it's worth it to mount an intake behind the motherboard? I have a space between the side panel and motherboard tray where a 60x10mm fan would fit, but I'm not sure if it would be worth the trouble. I sort of don't want to cut into my shiny new SLK3000-B, but would if it makes a difference.

I figure air just sort of sits back there and heats up, and I heard that the backs of the mosfets can dissipate a lot of heat.

I'm also slightly worried about extra noise, since I'm going for quiet with this build, but I'm sure I could find some 60mm fan that would be silent at 7v or 5v. Would such a fan even push enough air?
 
It is probably not worth the trouble. Not much heat can be transferred through the mobo. On top of that, you may get a false reading from mobo temperature detectors if there is some localized cooling where the detector is mounted. The sensor is being cooled, but nothing on the mobo is benefiting.
 
Right, I know about the temp report readings. I thought that some other stuff might benefit, like mosfets and the NB/SB, which are mounted directly on the PCB. I guess I'm watercooling the NB though, so...
 
Yes, it will make a difference. Placed a fan in my back side panel then cut a hole in
the Mobo tray behind the CPU socket. There was a very nice drop in socket
temps, no change in the on die sensor though of course.

And if you think not much heat gets transfered to the back side of the Mobo take
a look at this :::::: (DFI Lanparty nF4 Ultra-D)


' ' The next photo shows the back of the board. Drawing your attention to the center is the processor, glowing hot at 72.9 °C. When this image was taken ITE Smart Guardian showed a CPU temp of 43 °C.' '

2.jpg

http://www.bigbruin.com/reviews05/nf4thermals/index.php?file=1
 
Yes, heat is transferred through to the back of the mobo, not only at the CPU socket, but definitely around the power mosfets too. But cooling the mounting tray won't do much, you have to cut a hole in the mounting tray to circulate the air between the mobo and mounting tray. This is more for extreme overclocking, I doubt it would provide much benefit if you are only doing a modest O/C.
 
I've done this, and I'm happy with the results. I got a 4 degree drop in idle temps from 45 to 41 and a 5 degree drop in load temps 58 to 53. It wasn't too hard to do either, just used a drill, a file, and some tinsnips. Those temps are on a prescott, dunno if it will do much for your chipset
 
But cooling the mounting tray won't do much, you have to cut a hole in the mounting tray to circulate the air between the mobo and mounting tray.
Yeah, that was the plan.

I'm shooting for somewhat extreme overclocking...a voltmodded AS8-V and watercooling.
 
An alternative would be to shoot air down the back of the motherboard using 1 or 2 PCI slot blowers - you know, the useless kind that don't move much air. The reverse of a PCB isn't going to be a very good heatsink but some air convection will help the mosfets/southbridge a bit.
 
any guess of how much space is between the tray and side panel? typically?

15 mm?
 
Like I said I have done this and while it does help to keep things cooler however I wasn't able to squeeze any more performance out of my board in doing so.

NewCase3.JPG
 
I have a vent built into my custom built case that blows right onto the center of my cpu's backside.
I've never measured the difference in temps, but that's not why I did it. Every solder joint on your board is a sink to the component on the front (not that solder is an awesome heat conductor), so why the heck wouldn't one do this???
 
johan851 said:
10mm on both Antec cases I've measured.

It's 22mm in my cases, plus another 6mm between the tray & board itself.
A regular 25mm thick fan fits nicely. Perhaps it's wide because of the slide out mobo tray.

Like EC was saying, I wasn't able to squeeze any more from my system with
the backside fan. But I doubt a cooler running CPU socket is a bad thing.
 
i was thinking of doin that but i dont have much space betweent he right side of my case and the edge of the desk.

great idea though get some airflow behind the mobo
 
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