# MOSFET Cooling help.



## suraswami (Apr 14, 2008)

I am playing around with my test pc (in my signature - Jetway board).  I am trying to get a stable OC out of my 5600.  Last 2 days its hot here in Southern california and I have to drop my OC a few numbers.  Currently @225*14 with memory running at DDR2 747.

I read online it might be because of poor quality/heating Mosfets/VRM.  I have attached a picture of the mobo.  The marked position is the mosfet area right?

Right now I have squeezed in a 80mm TT fan and seems to do the trick.  What other methods are efficient?

Help please.


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## sneekypeet (Apr 14, 2008)

stick some ramsinks on em and see if the temps go down. it will help the fan get more of the heat away!


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## Solaris17 (Apr 14, 2008)




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## Darknova (Apr 14, 2008)

The MOSFETs are the smaller chips in that are yes, the larger ones are...well I don't actually know, but they don't require cooling.

You want to pick up some Enzotech MOSFET heatsinks if you for them if you can.

By the way, cooling of the MOSFETs is of the highest priority when overclocking, they can burn out very easily.


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## suraswami (Apr 14, 2008)

Solaris17 said:


>



I need to stick ramsinks for all those?


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## Solaris17 (Apr 14, 2008)

as darknova said i think they sell mosfet sinks but as he also said cooling fets is imparative so yes. besides its not that much 4 ramsinks at most.


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## Darknova (Apr 14, 2008)

http://www.sidewindercomputers.com/enmofocomohe.html


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## suraswami (Apr 14, 2008)

Darknova said:


> The MOSFETs are the smaller chips in that are yes, the larger ones are...well I don't actually know, but they don't require cooling.
> 
> You want to pick up some Enzotech MOSFET heatsinks if you for them if you can.
> 
> By the way, cooling of the MOSFETs is of the highest priority when overclocking, they can burn out very easily.



yeah this is a cheap $40 board that suprisingly have lots of OC features.  Similar to Biostar T-Force.  but I think has cheap parts and thats the reason it needs more voltage to push the cpu.  I tested with 2 cpus before I bought the 5600.  1. A64 3200 which runs default at 1.25V and can be pushed to 2.6 from 2 at 1.3V on a cheap ECS board.  But this one needs 1.35V
2.  X2 3800 windsor - same thing can be pushed to 2.2 from 2 from 1.2V to 1.25V on ECS but on this one I need to pump 1.3V and will not go even one single HTT after that.

For the 5600+ when I set the Vcore as 1.35V in bios, cpuz and Everest shows as 1.4V.


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## suraswami (Apr 14, 2008)

Darknova said:


> http://www.sidewindercomputers.com/enmofocomohe.html



I need to buy a thermal tape too right?

I have few unused Zalman ram sinks that came with VGA cooler.  I was thinking of cutting it to small pieces and stick it.


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## SuperStarr (Apr 17, 2008)

Then no need for thermal tape, that ZALMANs have some sticky sh*t on himself. Just paste it on 'FETs...


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## AddSub (Apr 18, 2008)

Anyone have any actual data on cooling MOSFET's vs. not cooling them? I always thought it was just a marketing gimmick by the motherboard manufacturers, especially DFI. I mean, considering most MOSFET's are rated at around 145C, 150C or even 175C, which means they can take the heat. I do like DFI motherboards and I own one of their LanParty series motherboards, which has heatsinks on MOSFET's, but I never bothered to take them off and check out the difference in overclocking. (It would probably be hard to put them back on.)


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## Spacegoast (Apr 18, 2008)

i think the swiftech MC21's will cover those mosfets. you can find them for pretty cheap. $10 i think.

edit: link http://www.frozencpu.com/products/5557/vid-86/Swiftech_MC21_Aluminum_MOSFET_Heatsinks_-_4_pack.html?tl=g40c16

2 should cover them all up


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## imperialreign (Apr 18, 2008)

AddSub said:


> Anyone have any actual data on cooling MOSFET's vs. not cooling them? I always thought it was just a marketing gimmick by the motherboard manufacturers, especially DFI. I mean, considering most MOSFET's are rated at around 145C, 150C or even 175C, which means they can take the heat. I do like DFI motherboards and I own one of their LanParty series motherboards, which has heatsinks on MOSFET's, but I never bothered to take them off and check out the difference in overclocking. (It would probably be hard to put them back on.)



some boards that use MOSFETs or VRMs are notorious for the chips running at thermo nuclear temperatures.  I remember reading an article somewhere that was describing how the VRMs on a dual-CPU Intel board were producing temps a little over 120C 

not saying all boards are like that, but some do require extra attention.  It matters not to me if the component is rated to be able to handle those kinds of temps; asides, the cooler the component runs, the better it performs, and the longer the component will live as well.


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## Darknova (Apr 18, 2008)

AddSub said:


> Anyone have any actual data on cooling MOSFET's vs. not cooling them? I always thought it was just a marketing gimmick by the motherboard manufacturers, especially DFI. I mean, considering most MOSFET's are rated at around 145C, 150C or even 175C, which means they can take the heat. I do like DFI motherboards and I own one of their LanParty series motherboards, which has heatsinks on MOSFET's, but I never bothered to take them off and check out the difference in overclocking. (It would probably be hard to put them back on.)



At stock you can quite happily leave your MOSFETs bare without any issues, but when you start upping NB and vCore you start running into issues as the MOSFETs burn out meaning no power gets to the CPU or NB, resulting in a dead board.
It's really not about gaining extra overclock, just keeping your board alive long enough to give you that massive overclock you are looking for.


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## SuperStarr (Apr 18, 2008)

Ok, but 'FETs are primary cooled by PCB of MoBo? Isn't that? Extra cooling is just (mainly) good marketing.


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## Darknova (Apr 18, 2008)

SuperStarr said:


> Ok, but 'FETs are primary cooled by PCB of MoBo? Isn't that? Extra cooling is just (mainly) good marketing.



Extra cooling is necessary for all overclockers.


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## SuperStarr (Apr 18, 2008)

Understand that, have some expirience.
I wanna say that neither heatsink can cool 'FETs more than PCB of MoBo. I think extra airflow (add some fans to blow on them) is effective more than adding any HSs....


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## Darknova (Apr 18, 2008)

SuperStarr said:


> Understand that, have some expirience.
> I wanna say that neither heatsink can cool 'FETs more than PCB of MoBo. I think extra airflow (add some fans to blow on them) is effective more than adding any HSs....



So you want to radiate the heat into the motherboard's PCB? No thanks, I'll take a copper heatsink radiating heat away from the board thanks. Heat = bad. The faster you can remove it, the better, be it CPU's, GPU's, MOSFETs, PCBs...anything, keep it as cool as possible.


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## trog100 (Apr 18, 2008)

things have to be cool enough.. not as cool as possible.. i aint gonna say what cool enough is but if things are designd to run at 150c they are okay at 150 c..

good design has some spare capacity.. cheap poor design dosnt.. the fancy heatsinks on more expensive boards are part spare capacity and part go faster stripes.. its hard to say how much of each there is.. i think a fan blowing on the general area is probably good enough.. 

120 c is bloody burn your finger hot.. if they dont burn your finger they are probably okay.. 

trog


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## trt740 (Apr 18, 2008)

http://www.sidewindercomputers.com/misimi.html these are good and are better made than this picture shows. they also come with adhesive.


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## Darknova (Apr 18, 2008)

trt740 said:


> http://www.sidewindercomputers.com/misimi.html these are good and are better made than this picture shows. they also come with adhesive.



I just ordered a set of the Enzotech ones to cool my RAM MOSFETs and any not covered by my motherboard cooling.


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## suraswami (Apr 18, 2008)

Hey I tried cooling the cpu area mosfets with a 80mm fan.  Then shutdown the machine for about 30 minutes.  Unplugged the 80mm fan.  Ran the system with full load (Orthos + Prime95) for 20 minutes.  Touched those mosys and they seem to work cool.  I can touch the mosy for a long time.  So I think they are pretty cool.  Anyway I left the fan on, extra cooling will not hurt, except for extra durt.

One thing that I found out with this board is it doesn't like any temp monitoring software.  When I leave the monitoring tool on and when the machine goes to hibernate and then wake up it hangs.  I removed the tool and the machine works fine.

But I will try one of those mosy hs.  Are those websites safe?  I always buy from egg, but they don't have any of those.  May be I will cut the Zalmans and try it out.  Will it void the warranty on the board?


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## suraswami (Apr 18, 2008)

I used A64CPUAssistant (both Lite and Full version), Coretemeter and Core Temp.  Everest works fine though.


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## SuperStarr (Apr 19, 2008)

Darknova said:


> So you want to radiate the heat into the motherboard's PCB?



No man, I understand You but i fear You don't understand Me... if You stick some HS on FET, HS will "mess" heat and when HS "fill" of heat, that will be problem. You will have heat sandwich on FET and for sure higher temperature.
Mabybe first 5 minutes temps (of FET) will be better but later... 



Darknova said:


> Heat = bad. The faster you can remove it, the better, be it CPU's, GPU's, MOSFETs, PCBs...anything, keep it as cool as possible.



FET's will for sure proceed heat on PCB of MoBo and that's relative huge area.
With airflow over FET you give him only extra cooling. You cool FET & MoBo' PCB... All that heat will be absorb from some outake fan and that's best way to deallocate heat. Thats why I like "ORB" CPU coolers. 

I hope now Yo understand Me.


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## rege (Apr 20, 2008)

I have to agree with Superstarr, most mosfets (like the ones on suraswami's board) don't benefit from having a heatsink on them.  They dissipate heat into the motherboard pcb because they have a metal plate at the bottom where they are mounted.  The top of these type mosfets also have a thick plastic insulation so they generally don't get hot to touch even if they are running hot, airflow around these type mosfet is more important and a heatsink might actually insulate them.  I once had an old fic via board that had the mosfets mounted vertically with heatsinks pressed against the metal plate of the mosfet, those heatsinks got very hot.

On the other hand some mosfets like the ceramic ones and the small surface mount ones found on gigabyte boards benefit from having a heatsink, they are much more dense and don't dissipate as much heat into the mobo.  You also need a fan or good airflow otherwise the  heatsink just gets hotter and hotter.


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## largon (Apr 20, 2008)

SuperStarr said:


> if You stick some HS on FET, HS will "mess" heat and when HS "fill" of heat, that will be problem. You will have heat sandwich on FET and for sure higher temperature.
> Mabybe first 5 minutes temps (of FET) will be better but later...


That makes no sense. That's pretty much like saying "CPUs are better off with no heatsinks". 






> FET's will for sure proceed heat on PCB of MoBo and that's relative huge area.


PCB is made of thin layers of copper and _plastic resin_ of which the latter is a very poor thermal conductor. So, a significant amount of the heat the fets create is conducted via the copper "plane" to the chip the fet feeds - such as CPUs, chipsets, RAM, etc...


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## suraswami (Apr 20, 2008)

This Abit board already have a Mosfet HS pre-installed.

http://www.uabit.com/index.php?option=com_content&task=view&id=32&Itemid=48&page=1&model=384

If the theory is right then abit engineers would not do that.  Or they should have removed the plastic layer.

Once again it depends on the design.


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## trog100 (Apr 20, 2008)

its possible that covering the mosfet motherboard area with a large heatsink might make things worse and stop the board area getting a good cooling airflow..

kind of six of one and a half dozen of another..  small individual heatsinks on top of each chip cant do any harm thow.. but the board itself does act like one big heatsink and take heat away from the little chips.. either way blowing cooling air on it helps..

a low power cpu device could be cooled the same if flush mounted and soldered directly to the motherboard.. the board itself acting as the heatsink

lets not forget big flashy looking heatpipes are a bit like go faster stripes.. as much to do with appearance as function.. no enthusiast is gonna buy a mobo without the bloody things functional or not.. 

trog


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