North Bridge and South Bridge NForce2 cooling

[Gizmo]

So, I thought I'd throw up some pics of the two mods I did to my Abit NF7-S for cooling my North and South bridges.

As I've already noted here, the cooling solutions for these chips on the Abit NF7-S and AN-7 boards are either non-existent or barely adequate for stock operation. If you are going to OC, you need to keep these chips cool to achieve stability.

For the North Bridge, I'm using a modified Cyrix 686 cooler. There are basically two approaches to fastening a heat sink or an HSF to a chip; use screws or use glue. For the NB, because there are already mounting holes in the board, I used screws.

To start, I disassembled the fan from the HSF. Then I lapped the base of the heat sink (it wasn't real flat). I used a piece of glass that was about 50% larger than the heat sink for my sanding block. Starting with 220 grit sand paper and working my way through 320, 400, and 600, I sanded the heat sink smooth, using the glass (covered with sand paper) as my working surface.

I then took a Radio Shack TO-220 style heatsink and lapped it, using the same process. (Sorry for the blurry pic, I was too darned close to the heat sink).

Edit: You'll note that the HSF has two holes in it. I put those there after I had lapped the heat sink, but before I took the pictures

[Gizmo]

Finally, I hand lapped both the NB and SB. I used a piece of glass about 50% larger than the chip surface for my sanding block, and did the same basic thing. I didn't bother with masking the area around the chip, because these chips have a plastic surface. If I had been lapping one of the older NF7 boards that had the chips with the metal core, I'd've masked off the area around the chip using double-sided tape to catch any debris.

There isn't (IMHO), much point in going above 600 grit on these, especially if you use some decent thermal compound like AS5. All in all, lapping these two chips and heat sinks took about two hours.

After all of that was done, it was time to mount the heat sinks.

I did the south bridge first, because it was the trickier of the two. The problem with mounting a heat sink on the south bridge is that, if your choice sticks up too far, it will interfere with cards in the PCI slot if you aren't careful. I did a dry fit with an old PCI video card to get an idea of where things needed to be. After that, I applied a thin layer of AS5, and two tiny dabs of super glue. I'm using super glue, because if anything ever happens I want to be able to get this sucker off without destroying the chip. Super glue is strong enough to be able to keep the heat sink in place under normal conditions, and brittle enough that a good twist will shear it loose without destroying my chip.

Finally, I mounted the heat sink using an eyeball alignment and good old fashioned thumb pressure. You don't want to sit on this heat sink when you mount it, but you do want to make sure you get a decent (15 pounds or so) amount of pressure on it.

Final pics of the south bridge heat sink showing its mounting in relationship to the PCI video card, and why you need to pay attention to the height of the heat sink. You will note that the heat sink is mounted a little off center. For this chip, that doesn't seem to be too much of a problem, since it doesn't actually generate a lot of heat (maybe a couple of watts). It just doesn't have any good way to get rid of that heat. Since the heat sink does cover the center of the chip, everything is good.

[Gizmo]

Finally, on the NB, I did a dry fit to the heat sink, to make sure everything fit. Then I pulled the heat sink off, took the old Abit HSF, and used that to mark where I needed to drill the mounting holes on the HSF. In retrospect, I should have drilled the holes first, and then lapped the heat sink, but I'm a dumb hill-billy. Sometimes I have to learn things the hard way. In this case, while drilling the holes scored the bottom of the heat sink in the area around the holes a little bit, it didn't hurt anything.

I drilled the holes using a drill bit that was just slightly smaller than the screws used to secure the fan to the heat sink. I then took a rubber grommet and cut it in half. Then I put a coat of AS5 on the chip, applied the heat sink, and got everything lined up. Finally, I used one of the screws that secured the fan in place, ran it through a flat washer and half the rubber grommet, through the mobo, and into the heat sink. I then repeated the operation for the other side. After that, it was just a matter of torquing the screws down evenly on the heat sink, and then remounting the fan using the two remaining screws.

Here it is, mounted to the chip. Note that clearance to the CPU socket can be an issue, particularly with the larger HSF assemblies for the CPU. Keep this in mind when choosing the HSF that you are going to use for your NB.

For me, this is a temporary solution on this mobo, as I have a Maze3 WB that I bought from Spyder heading this way soon, and I will be mounting that. (Hey Spyder, check your PM! )

[Daniel ~]

Front page Big Guy!! As clear as a bell! ":O}

[Gizmo]

Cool!

[Allan]

Looks good Gizmo!
I see you have water cooling, you should consider water cooling your NB instead of air coolig it..

[Gizmo]

Originally Posted by Allan

Looks good Gizmo!
I see you have water cooling, you should consider water cooling your NB instead of air coolig it..

As I mentioned in the article, I'm just waiting on my water block from Spyder. I said Maze 3; it isn't, it's the Maze Chipset.

I'm beginning to become a little concerned that something has happened to Spyder, though. He hasn't been on since the 21st, and he was going to try to ship the block around about the 15th or so. After seeing the pics of his wrecked car, I hope he hasn't had another encounter with a reckless driver.