Making VRM heatsinks?

[_j03_]

Hi,

So my mobo is Asus M4A77T and I've decided to do heatsinks to its vrm's. I'm going to use Athlon 64 x2 stock cooler for this and cut pieces from it. I'm just not 100% sure that which all components I should cover with the heatsink and what kind of thermal paste I should use to stick them into it.

I can't find that damn thermal paste glue from anywhere in here finland... Oh, there is one store which sells it 18€ but you have to wait for it 2-3 weeks. Just so stupid. So is there anything else I could use, how about those thermal pads, do they hold them in place?

And here's a picture where I think the heatsinks would come on. So is it like this...?

 

[TheQuadFather]

well my 785G version of that board came with a sink, an it sits over the parts left from the parts you pointed out.

 

[Bobnova]

The items circled in red are the inductors/chokes, they don't need heatsinks.
The mosfets are right under the arrows.

 

[_j03_]

The items circled in red are the inductors/chokes, they don't need heatsinks.
The mosfets are right under the arrows.

Oh, ok, thanks

 

[larrymoencurly]

Ordinary silicone rubber sealer works well for holding heatsinks and conducting heat, yet unlike with thermal epoxy, you can easily remove the heatsinks by cutting through the glue. Silicone rubber sealer should conduct heat better than thermal pads because the glue can be made thinner.

If you can solder, maybe it would be even better to solder a piece of 1-2mm thick copper to the large metal tab of each MOSFET. Use a separate piece of copper for each MOSFET, and don't let the pieces touch one another.

 

[Bobnova]

You want thermal tape.
Silicone goop between heatsink and mosfet may insulate more then it cools, you don't want that.
Soldering to those tabs isn't likely to happen, they're on a beefy ground plane, you're looking at a very hardcore soldering iron at the least.

Just get some thermal tape, presto! Heatsink sticks, and it's built to transfer heat well.

 

[_j03_]

You want thermal tape.
Silicone goop between heatsink and mosfet may insulate more then it cools, you don't want that.
Soldering to those tabs isn't likely to happen, they're on a beefy ground plane, you're looking at a very hardcore soldering iron at the least.

Just get some thermal tape, presto! Heatsink sticks, and it's built to transfer heat well.

Ok, thanks They won't cost much either and the availability is also much better it seems.

What about the heatsinks, is it better to do like one big heatsink or separate for every one of them? Or one heatsink for two of them, like 5 heatsinks in total?

And just to make sure since that last pic got terribly wrong, do I NOW got the right ones circled ?

 

[TheQuadFather]

yep you do have the right ones circles, and yes cover all of them, probably best going for one large sink.

 

[Theocnoob]

yep you do have the right ones circles, and yes cover all of them, probably best going for one large sink.

One big sink will conduct the heat away more evenly. You can't do that though because if you look closely the capacitors (silver, round, red writing) intrude into the Mosfet area in such a way on the left and right, that if you used 1 giant sink, part of both rows of Mosfets would not be covered. See what I mean? It'd have to sort of run along the middle and not cover the extreme right and left edges respectively to clear those capacitors.

Thermal tape should work for you .

Gonna have to make several smaller sinks though. Either that or dremel clearance for the capacitors.

I DID make you a diagram but OMG photobucket upload links are broken on April 1st! What clever and original hackers these kids are...
Do something creative... Buggers...

Please post pics! You know, after you're done. Nobody's ever made little VRM sinks out of a hacked up bigger sink on here AFAIK...

 

[SupaMonkey]

http://www.enzotechnology.com/mos-c1.htm

This is what you need.

 

[Theocnoob]

He wants to make his own . We support insanity.

 

[_j03_]

http://www.enzotechnology.com/mos-c1.htm

This is what you need.

Im doing this by myself for fun. Also I don't feel like ordering those from abroad and then paying 20$ for shipping them.

 

[Theocnoob]

 

[_j03_]

Yep, this is how I'm going to do it. Total of 5 heatsinks then.
Though I could make that big one too, and with drill make room to those capacitors.
Is there any cons in painting the heatsinks, is normal spraypaint ok? Might it block the heat from vaporising or something like that?

 

[QuietIce]

Personally, I'd go with two larger heatsinks (four chips each) and one smaller one (two chips) so you've got more surface area. But five smaller sinks will work, too.


As long as you follow normal painting practice (two thin coats) it shouldn't hurt too much to paint them. A thick coat might be a problem - and I'm assuming you'll use enamel, not latex or oil-based. Metal dies work better but can be expensive and hard to find.

 

[_j03_]

Personally, I'd go with two larger heatsinks (four chips each) and one smaller one (two chips) so you've got more surface area. But five smaller sinks will work, too.


As long as you follow normal painting practice (two thin coats) it shouldn't hurt too much to paint them. A thick coat might be a problem - and I'm assuming you'll use enamel, not latex or oil-based. Metal dies work better but can be expensive and hard to find.

Thanks !

Have to see when I've got time to start working on these, even though this ain't so time consuming. Currently I'm middle of an exam week...

 

[Theocnoob]

Personally, I'd go with two larger heatsinks (four chips each) and one smaller one (two chips) so you've got more surface area. But five smaller sinks will work, too.

Damn your superior spatial reasoning.. And likely superior Tetris skills.

Yes much better idea than mine.

 

[_j03_]

Well what about the idea of one big heatsink, and then just drilling a little hole to those caps?

e: a pic to make clear what I mean. Even if I would make that 2+2+1, I would need to make these holes to the caps on the right side.

 

[Theocnoob]

Well what about the idea of one big heatsink, and then just drilling a little hole to those caps?

e: a pic to make clear what I mean. Even if I would make that 2+2+1, I would need to make these holes to the caps on the right side.

That would be fine. Best option really.

BTW when you put the thermal tape on, you can basically just use one long strip cut to fit the bottom of the heatsink.

 

[QuietIce]

Well what about the idea of one big heatsink, and then just drilling a little hole to those caps?

As Theocnoob has said, that's probably the best option because it has the highest surface area - though I don't know if solid caps get hot or not?

But, really, even the five smaller ones would work fine.