Cpu Fanwich?

I've saw a mod in on overclockers.com called fanwich where a guy but a fan on the back of his video card. He said it helped a lot with temps. I was wondering if I could put a fan on the back of my motherboard behind where my CPU would be if I would see a drop in CPU temps? Any one ever try this?

I would say yes that it would work. but how will yu mount it? perhaps mount it to the back of the mobo tray. and use a 120mm, i think that would help. maybe even get a 3-5C drop. Maybe....

The GPU of a videocard is mounted directly to the PCB of the card, so it heats up the card a lot. This makes cooling the GPU from the back of the card work fairly well. A CPU sits up away from the mobo in a soccet, so it doesn't heat up the motherboad nearly as much. Putting a fan on the back of the mobo would help things a bit, but it won't do much.

Personally, I don't think it'd do anything at all. If you have a temp probe mounted on the motherboard, and the fan blowing on the back of the motherboard onto the CPU area, then it'd really only change the probe's readings, not the actually temps of the CPU. If it were to change the CPU temps, it woudln't do a whole lot.

A fan on the back still wouldn't be a bad idea though. It would help a lot more in the mosfet region rather than the CPU. The northbridge and southbridge are mounted directly on the the PCB as well.

I know several folks ( myself included) who have been running fans on their motherboard trays for quite a while.
A 120mm works the best and mounting it on your sidepanel exterior gives the fan some room to breathe.
Blowing in seems to give slightly better results than sucking out.
When you cut the motherboard tray, try to include the northbridge and mosfet area if possible.
When I had my Asus board and could access the on-board diode, the fan mod was good for a temp drop of about 3-4 degrees.
With my new NF7-S I have to rely on just the socket thermistor, but I still think it's a worthy modification.

Right on. From what I've read I think I'm going to do it. One quick question. Mosfets are all the capacitors around the socket of my CPU?

They're actually all those little black chips next to the capacitors. The capacitors are...well, capacitors.

OK thanks. What do they do that they heat up so much?

ClarkKent said:

OK thanks. What do they do that they heat up so much?

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They act as valves to control the electricty that powers the CPU

energy cannot be created or destroyed...so it has to go somewhere, heat.

If the mosfets become to hot, they don't regulate voltage to the CPU quite as well as normal. at least, when overclocking, we have had this problem arise quite a few times.
And you don't want your voltages fluxuating, or getting the wrong ammount of voltage. to much voltage, means, more heat. not enough voltage mean...if your overclocking...instability. mix both together, to much, to little, your CPU just won't like it. and all in all, its bad for sensitive electronics.

So, some of us, has cut Heat Sinks, and put them on the Mosfets, and some have put fans ontop those heatsinks ( or at least, get quite a bit of air-flow on the Heatsink, that is on the mosfets )

And those who have put heatsinks on them, have noticed an increase in stability in their computer. and they would use programs, to monitor their voltage to their CPU. With Heatsinks, the voltage wouldn't jump around as much as normal, giving the CPU a much cleaner input voltage.

and the reason they get hot?

Well, Mosfets are kinda like transistors, that do a different job. the mosfets in your computer, make sure that the voltage you tell to go to the cpu, is what you tell it. it has to do work ( basicly ) to make sure it doesn't sent to much, or to little voltage. and to do that work, also require voltage.

Also, think about it. say 2 volts is going into your mosfets, but you only want 1 volt going out, to your CPU...what happens to that other volt of electricity that you do not want? simple....heat.

sorry for the long post here. felt like making an informative post again. havn't done so in a while.

so, trying to cool your mosfets, can be just as important as cooling your CPU, and GPU, and nortbridge, and at times, can be more important than your southbridge.

So it would be best to position my CPU fanwich so that the air is blowing on the back my CPU and mosfets. By cooling my mosfets I should see a more stable Vcore? I like the sounds of this mod more and more. I hope it all works out.

That original "Fanwich" article I did way back when did indeed drop temps. the thoery was proved yet again when I recently wrote my "Vantec Fan Card, Revisited:" article. I modded a Vantec fan card to blow down, rather than up, and mounted it behind my 9800 XT.

With the onboard thermal monitor the XT has, I was able to see how much the temps were effected, which was about 8 degrees Celcius.

I've taped probes to the backside of the motherboard centered under the CPU socket, and while not as hot as the backside of the video card (due to the space under the socket as mentioned), it still would benefit a little to put a fan there, and definitely could help in the areas around the mosfets and northbridge (moreso the mosfets).

I don't know if the gains would be worth the effort though. I suppose it might depend on how well the rest of the case flows air.

zexmarquies01 said:

Mosfets are kinda like transistors, that do a different job.

Click to expand...

MOSFETs are transistors. MOSFET = Metal Oxide Semiconductor Field Effect Transistor.

Doesn't the blowback from having a fan blowing so close on a solid object (PCB of the vid card in this case) cause excessive noise, less CFM, and lower fan life?

there was a big article over at [h] awhile back about this, i think they were seeing 6-8c drops as you said on your video card. but this was on their cpu temp

klath said:

Doesn't the blowback from having a fan blowing so close on a solid object (PCB of the vid card in this case) cause excessive noise, less CFM, and lower fan life?

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No on the excessive noise, probably. These are low CFM fans.

Yes on the CFM, but you are still doing a lot more good than if there weren't any fans on there at all...

Yes on the lower fan life (I guess), but when's the last time you replaced a fan because it died of old age?

ClarkKent said:

I've saw a mod in on overclockers.com called fanwich where a guy but a fan on the back of his video card. He said it helped a lot with temps. I was wondering if I could put a fan on the back of my motherboard behind where my CPU would be if I would see a drop in CPU temps? Any one ever try this?

Click to expand...

Yes I have here is a picture. I used a Zalman 80 X 15mm slim fan.



I cut a hole in the motherboard mounting panel (After Careful measurements of course). then cut a hole in the side panel (Again measure twice cut once)

klath said:

Doesn't the blowback from having a fan blowing so close on a solid object (PCB of the vid card in this case) cause excessive noise, less CFM, and lower fan life?

Click to expand...

So would it be better for me if I could get more distance between the back of the motherboard and the fan? My case has plenty of room on the other side to give as much room as I need. I want best cooling and don't think that a shorter fan life is really a problem.

JKeefe said:

No on the excessive noise, probably. These are low CFM fans.

Yes on the CFM, but you are still doing a lot more good than if there weren't any fans on there at all...

Yes on the lower fan life (I guess), but when's the last time you replaced a fan because it died of old age?

Click to expand...

Hmm, take a regular 80mm (heck, any size) and plug it into PSU. Mentally notice the noise. Then place it on the desk so it's blowing on the desk. The pitch and magnitude of the sound increases substantially. I'm worried about the sound then anything else. I have a 80mm vantec stealth on 12V and I think it's the loudest component in my case. Once I get my Fan Master, I'm going to quiet that fan down.