MOSFET Cooling (thermal adhesive or tape question)

[RedCell989]

I am realizing that the 4+1 VRM isn't exactly a feature on my motherboard. It was fine when I was running a first gen Phenom X4, but now that I upgraded to the 1100T something needs to be done. I don't have the budget to upgrade to AM3 board with 8+2.

On my ASUS M4A785-M motherboard there is no VRM/MOSFET heatsink or any form of cooling whatsoever except ambient air and maybe an unintentional breeze from the CPU sink/fan. There are also no holes for attaching a aftermarket heatsink with pushpins.

I have devised a plan to purchase 2 EnzoTech MST-66 MOSFET heatsinks and through some modification make them fit within the area needed, but the problem I am having as far as attaching and anchoring the heatsinks go, is what to use.
Will a thermal tape be durable and strong enough? is there any thermally conductive adhesives I could use that are not electrically conductive (just to be safe)??

I also plan on attaching a couple 25mm fans to the sides of the heatsinks if I can anchor them well enough.

Any help/ideas/experiences would be greatly appreciated! Thanks!

 

[SMOKEU]

Good luck finding thermal tape or adhesive for sale, I tried just about every computer shop I could find and none of them sold it.

Some good quality thermal adhesive would be ideal if you can find a shop that sells it, and the adhesive tends to stick better than the tape does.

25mm fans are going to be extremely noisy to even move a small amount of air, so you'd be best off improving your case ventilation instead. Maybe cutting a hole in the side of your case and mounting a 120-140mm fan on the side blowing onto your motherboard would be the way to go.

 

[RedCell989]

Ya I just noticed 25mm fans aren't really ideal. There is 2 case fans really close to the VRM area:

I am thinking I can direct some air towards the VRM from at least one of these fans, or both.

 

[SMOKEU]

I think that if you have some small heatsinks connected to the VRMs, and you have reasonable case airflow then I don't see why you should have any problems with VRM temperatures. If the VRM heatsinks feel hot then you know they're connected properly to the VRMs.

 

[RedCell989]

Ya I was considering these as well: http://www.performance-pcs.com/cata...e=product_info&cPath=54_197&products_id=23308

But I wasn't sure if it would be enough. Everything I have read about trying to run the AM3 X6's on my board has strongly suggested to get as much VRM cooling as possible, ideally with some sort of direct & active airflow involved.

I finally found some Thermal adhesive that doesn't conduct electricity as well: http://www.sidewindercomputers.com/araltherad.html

I think I will still get the bigger enzotech sinks anyways, they would provide substantially more surface area, plus its fun to cut stuff

 

[capttripppp]

You could put the heatsinks on, and mod some kind of duct forcing air to flow over them

 

[RedCell989]

Ya im pretty good with building fiberglass enclosures and custom tubes (another hobby) so this will actually be fun to play around with

 

[Diggrr]

I saw the title and came in here to suggest the Enzotech sinks and the Arctic Alumina. I used their 1" tall chipset sinks and AA combo on my mITX rig for both chipsets (one chip comes bare from Intel and burnt me!).

Just make sure to lay the case/motherboard down level to keep the sinks from scooting out of place before the curing has set hard. The bond is not instant, but it's good to have some working time with the adhesive. Keep it thin too, but not so thin as to be see through. I used piece of plastic card as a putty knife to apply it.
When I did full ATX, I'd make 'glass scoops that divert half of the back fan airflow to the mosfets, so enjoy that bit of fun!

 

[RedCell989]

Thanks for the tips! Just ordered them today and drawing out/planning the best way to redirect some airflow over the enzotech sinks. Got the 10/pack of enzotech MOS-C10, and non electrically conductive Arctic Alumina TIM for 16.99 shipped . Will post a followup and pics when I am done!

I really enjoy the overclockers.com forums because I don't see hardly anyone saying "just buy another board..." which is refreshing for those of us on tight budgets making due with what we have. Thank you!

 

[Diggrr]

Overclocking started as a way to extend the life of super expensive computers. Now that the computers are much cheaper, it's become a way to get ahead of the curve and beat the tar out of the big boy's systems while often spending less.
You'll find people here that have been beating on computers for 25 years (like myself), and we can almost always find a use for older hardware. Us old farts tend to have less of a "disposable" attitude if you will....

Looking forward to the pics!

 

[Mpegger]

Ditto with the Enzotech heatsinks. I've used them alot on various Mosfets in my systems. Even have the mosfets on my 560Ti with them.

 

[RedCell989]

So I finally got finished with this little project. Was super busy with Midterms at school, plus I decided to wait for my new cpu cooler to arrive in the mail because I had to completely pull the motherboard for that anyways.

I decided to not redirect the rear case fans airflow, after studying it quite a bit and thinking it over I came to the conclusion that due to the angles required, the size of my case, position of everything after I installed my cpu cooler, and the cpu cooler itself, it would not be very efficient, and might actually harm some other components within my case.
Once I installed my cpu cooler it also became apparent that the new mosfet heatsinks would now be benefiting from the cpu coolers airflow. If you can see from the pictures the cpu cooler fan hangs over a portion of all the mosfet heatsinks, and after testing I discovered they were getting quite a bit of airflow from this.

The only things that sucked for the most part was that I had to remove my RAM and use some backups until I figure out how to fit the RAM with their heatsinks under the new cpu cooler. And I guess the biggest thing was that I went back to my Phenom 9500 X4 processor for now because after testing it just ran Ableton Live and Cubase a whole lot smoother and faster even with lower clock speeds.

Used Arctic Silver 5 for processor, spread over processor in a pretty thin layer using the spatula/mixing tool the Arctic Alumina came with. Arctic Alumina non electrically conductive ceramic formula (stuff is strongggg accidently welded a zip tie to the surface I was working on, couldnt get it off)

So ran my computer at my usual ASUS preset 10% overclock profile (from 2.2 - 2.4 ghz) and after an hour my system leveled off at:

Idle

Motherboard temp: 30-31 degrees Celsius (fluctuates)
CPU temp: 32-33 degrees Celsius (fluctuates)

Under full load in Ableton Live (100% processors used at constant)

Motherboard temp:33 degrees Celsius (constant)
CPU temp36-37 degrees Celsius (fluctuates)

These temps are a decrease from low to mid 40's with previous setup.

So all in all, not too bad. Looking forward to overclocking further in the next few days, and testing my systems limits.

 

[Bobnova]

Those are the inductors, the mosfets are the flat things with two legs and a stub on one end and a slab of metal stick out on the other end, right behind the inductors.

 

[madhatter256]

That's kinda funny but it's ok. Cooling those inductors will help, too, but you really need to get those mosfets cooled down a bit...

 

[Bobnova]

Yeah, inductors definitely contribute to general motherboard heat. They don't generally overheat and pop though (it's possible, voltmodding GTX580s for vMem adjustment will generally fry the inductors).

I'd slap some on the mosfets too.

 

[RedCell989]

Wow... lol... thanks though... guess i will be getting more of those heatsinks because those suckers aren't coming off anytime soon. Can anyone point me to a decent general motherboard schematic or layout? I guess I totally blew that one... how embarrassing

 

[Diggrr]

Here ya go, marked them with red rectangles for ya.
Don't sweat the learning curve either...the 8 pin ones you bought probably wouldn't have fit them, you'll need the 4 pin ones.
Make sure not to glue them on touching that metal bit at the bottom of each mosfet, only on the black casing...can't quite tell if that metal is higher than the black part with this recklessly sto..uh, borrowed pic.
Pic credit goes to Newegg©

Better to ask for help than to stumble in blindly and kill a board!

 

[Bobnova]

The metal bits of the mosfet will be lower, not a whole lot lower, but at least 0.5mm to 1mm.
If space is an issue you can glue one sink to both mosfets of the pair, half heatsink is better than none.

 

[Neuromancer]

yeah mobo manufacturers cover it all up with one sink anyway.

 

[madhatter256]

Which is why you use non-conductive thermal paste/pad...