How to attach an enormous HSF to a NB/GPU

[DigitalN.]

many thanks to Geeky1, the orginal poster of this, Orignal Thread (link)

Ok, I've mentioned this to a few people, so I figured that I'd post a thread on how to attach a heatsink large enough to get an Approved-By-Mongo stamp to your northbridge and your video card, using the stock mounting holes. I used one method on the northbridge, and another on the GPU. Either one can be used for mounting a heatsink to either chip, it just depends on the size of the heatsink you want to mount.

// LEGAL DISCLAIMER //

Neither I, nor Neowin.net will be held responsible in any way should you damage your computer by following this guide. Any modifications made to your hardware can void your warranty, and could possibly damage the hardware.

// END DISCLAIMER //

Let's start with the northbridge.

The heatsink is a Coolermaster DP5-5G11A 50mm square unit that's rated for "Intel PIII CuMine up to 1.0 GHz P III Tualatin up to 1.5 GHz PIII Celeron up to 850 MHz and higher AMD Athlon up to 900 MHz Duron up to 900 MHz K6-2/3 up to 600 MHz". This heatsink is perfectly sized for a northbridge cooler, as it's got a small enough profile that you can use giant CPU HSFs (like the SLK-900A in the picture) with huge fans (a 92x25mm in my case) without clearance issues. I was originally going to use a 60mm square AMD retail HSF, but it was too big to work with the SLK-900A.

The drawback with this heatsink is that it has two little lips on the base, which you can see in newegg's pictures of it (didn't want to use huge amounts of their bandwidth with remote linking...). Those will have to be removed to mount it on the chip. 120 grit sandpaper works well for this. I suggest that you lap the base, as mine was way out of whack, and I suspect that given that it's a cheap aluminum extrusion, that they're probably all like that.

Anyhow, you can see my mounting system in this pic, which consists of a piece of steel that I cut to fit the slot left by the standard clip, and which has holes drilled in it to allow a bolt to pass through it.

In the above pic, you can see the underside of the board, and the rest of my mounting system.

And this pic shows the clip that I made, and how it's mounted in the heatsink. It's simply held in place by the clamping force of the nuts pulling the heatsink down onto the northbridge, and it's in the same channel left by the standard clip. Also note that the reason it has the splotchy appearance that it does is because it is starting to rust. Since I used uncoated steel, it's got a bit of surface rust on it. I'm not going to worry about it, since it's not a big deal. But, if if bugs you, either use stainless steel, or paint the clip. Don't use aluminum, as it's not springy enough. The piece of steel i used is ~ 1/16" thick, and that's thick enough that it has basically zero give when bolted on, which is a good thing in this case because it allows me to clamp the heatsink down firmly. Just be sure not to over-tighten the heatsink, or you'll probably break something.

Parts list for northbridge heatsink:

1x Coolermaster DP5-5G11A heatsink, lapped

1x Top Motor/Dynaeon DF1205BH 20cfm 50x20mm fan (optional)

2x 1" 6/32 phillips head zinc plated machine screws (6 if you go for the optional fan)

1x Steel or stainless steel plate, ~1/16" thick, and at least 1/4" wide x 3" long (that's a bit longer than necessary, but not much)

2x 6/32 size nuts

2x 6/32 size metal washers

2x large neoprene rubber washers (for insulation). Make sure that the hole in the washer is not big enough to allow the metal washer to pass through it, otherwise you'll short something out.

2x small neoprene rubber washers, trimmed to fit to insulate the top side of the board (these aren't necessary, and I just used them as a precaution. They don't actually do anything, but they go on the screw before the heatsink does, so that they contact the board)

Assembly:

1. Lap the heatsink. Start with 120 grit to remove the lips, and make it flat. Once it's flat, jump to 220. Carry this through 400, 600, and 1000. You can go to 2000 if you like, but it's unnecessary. If you don't know how to lap a heatsink, ask and someone here will help you out. One thing I will say: DO NOT, DO NOT, DO NOT apply any kind of wax or polish to that heatsink after it's been lapped. I know you want that mirror finish. You know what? Would you rather have a mirror finish, or a high-performance cooling system? Polish and wax fill in the microscopic pores in the metal, and interfere with heat transfer. DO NOT use them, period.

2. Measure the steel to cut the clip. DO NOT cut anything yet.

3. Mark the places to drill the holes in the clip for the bolts to pass through. The easiest way to do this is to place the old northbridge cooler on the sheet, and use it as a template to mark the holes.

4. Drill the holes for the machine screws. You'll want to use a bit that's just slightly larger than the diameter of the screw.

5. NOW you can cut the clip. Depending on the size of the sheet you got, this may involve just trimming the ends, or actually cutting it out with a dremel or a hacksaw.

6. Deburr the edges of the clip with a file/sandpaper to remove any sharp edges. Chamfer the edges of the bolt holes by placing a larger bit on the hole, and turning it a few times by hand. Your goal in doing this is just to remove the metal burrs from the hole, not make the hole bigger, so you don't want to use a drill to do this, and you don't need to press down on the bit super super hard, either.

7. Check the clip to make sure it fits the heatsink.

8. Clean any old thermal compound off the northbridge, and replace it with new stuff.

9. Assemble the thing... Turn the board over, so the back is facing you. Put down the two large rubber washers first, followed by a metal washer on top of each of the rubber ones. Drop a bolt through each hole. Hold the bolts in place with one hand, and flip the board over so it's right side up. Now you can put the two small rubber washers on, if you want to. Then put the heatsink on, put the clip over the bolts, and bolt it down. tighten it down so it's finger tight at first, gradually tightening down one side and then the other, so as not to put uneven pressure on the chip. If it's still a bit loose, grab a wrench and a screwdriver, and tighten down each side a bit. Check to see if it's still loose. If it is, repeat this last step as necessary, being careful not to over-tighten it. If you can't pull the heatsink up any measurable amount, it's tight enough.

10. You're done, unless you want to use the higher speed fan. In this case, just use the 4 extra 6/32 screws to screw it down; since the fan holder is plastic, having screws that are tapped correctly is not important, as the screws you use will simply tap their own holes as you tighten them down.

The Images (I linked them, just click)

Picture #1

Picture #2

Picture #3

Now for the GPU cooler.

The heatsink is an Ajigo Copper/Aluminum hybrid heatsink that is one of AMD's retail HSFs. It's attached to a Radeon 9700 Pro. The heatsink you use is going to depend on how much space you have on your video card, and how many PCI slots you want to give up. This particular cooler takes up 2-3 PCI slots. a typical 1u hsf will take up 1-2.

Just keep in mind that for the following attachment method, you will need a heatsink whose base is at least a bit larger than the horizontal distance between the two heatsink mounting holes on the PCB. Also keep in mind that you will have this thing hanging off your video card. Weight is a concern here, folks. I would not use a solid copper HSF, and I'd stay away from anything that weighs more than 400g, but that's just my preference.

Anyhow, the mounting method on this is dead simple:

(see attached images)

I tried using compression springs and other exotic mounting methods, but unfortunately I couldn't get anything to hold the heatsink tight enough. The drawback to my method is that if you are not very careful when tightening the screws down, you can (and will) destroy your card. If the card starts to bend, it's too tight.

(see attached images)

This image shows the actual mounting method- the two holes on the sides of the heatsink are 4-40 tapped, 1/4" deep holes. There are two variations on this method, btw. You can either drill most of the way into the base, and possibly have to trim your screws or use a few extra washers, or you can drill through the base, and not worry about screw length. The drawback to the latter method is that you will damage/destroy some of the fins on the heatsink.

Parts list for GPU heatsink:

1. heatsink of your choice, as long as the base is wider than the mounting holes for the heatsink on the video card

2. 2 4-40 machine screws, length will vary. They're so cheap that you may just want to pick up a couple different lengths.

3. 2 neoprene rubber washers (the larger the better. In the case of the 9700, I had to use ones that are the same size as the metal washers above them, due to the proximity of SMD devices to the mounting holes)

3. 1 4-40 tap and bit set

4. 1 tap holder thingy (I can't remember the name of these things; they look like some kind of weird hand drill or something. They have a chuck that the tap goes in, and a handle that you turn to turn the tap; you cannot use a drill with a tap; this must be done by hand. Ask the guys at the hardware store, they should be able to get you what you need...)

Assembly:

1. Test-fit the heatsink to make sure it'll fit.

2. Measure the spacing of the holes on the card, and mark the corresponding areas on the base of the heatsink, so you know where to drill.

3. Drill the mounting holes in the base of the heatsink. If you don't want to drill all the way through the heatsink, mark the bit with masking tape, so that only a length of the bit equal to the depth that you want is uncovered at the end. The best policy is to make it as deep as possible without going through the base of the heatsink. When drilling the holes, make sure that you make them straight. Crooked holes will cause problems.

4. blow out the holes to remove any metal chips, chamfer the edges, and tap them. You tap a hole basically the same way you put a screw into it- you put it in and turn... Just go slowly, do not put sideways force on the tap or it'll snap and you'll be in a real mess then, because you'll have to drill it out and re-tap it with another tap. It is normal to encounter some resistance, but do not force it. It's one of those things that just takes practice. My grandparents own a machine shop; the first time I tapped a part, I broke 6 taps in the space of 30 minutes. I have never broken one since then. You might want to pick up a piece of metal to practice on; If you do, I'd suggest aluminum, since it's soft. Also make sure it's at least 1/4" thick.

5. Mount the heatsink; The procedure is very similar to what it was to mount the northbridge heatsink. After cleaning the chip and applying fresh thermal compound, place the heatsink base up next to the card, flip the card over, and set up one hole with a rubber washer (this will touch the card and serves to insulate it so you don't short it out), a metal washer (on top of the rubber one), and a bolt. Leave the other hole alone for now. Position the card over the heatsink, line up the hole with the bolt, and tighten it down, just so that the bolt is in the hole securely. DO NOT tighten it down all the way. All you're doing is holding the card in place. Now grab the other bolt, and put down the other rubber washer, followed by a metal washer. Line up the other hole in the heatsink with the mounting hole in the card, and put the second bolt in. Again, tighten it down just enough to hold the card in place. Now start tightening down the bolts. Tighten them down just until they're touching the washers (not putting pressure on them) and stop. Now, you have to be careful. Tighten them down by turning 1/4 or 1/2 a turn at a time, going to the other bolt, turning it 1/4 or 1/2 of a turn, and then repeating the process. After each cycle, check to see if the heatsink is snug. As soon as it is, STOP. Look at the card and make sure it's not bowed or bent in any way. If it is, loosen the bolts by 1/4 turn each, until it's no longer bowed.

You have just installed a monstrous heatsink on your video card.

As for performance, with that heatsink, my 9700 Pro runs within 10*F of ambient at the stock clockspeed.

The Images (I linked them, just click)

Picture #1

Picture #2

Picture #3

thanks again for Geeky1's permission to post this!

[ootput]

Very informative (Y)

Only criticism I have is that it's kind of hard to follow without intermittent pics. The linkies you provided were fine, but it's easier on the eyes to break up the large chunks of text with images that pertain to the instructions.

Nice job, though.

[Geeky1]

Thanks. I would have distributed the images through the text, and in fact it was that way originally, but then the guys I was using to host the images started having issues, so I had to resort to attaching them to the post itself. :no: :(

[Nelsinho]

very good job thanks for DigitalN & Geeky1 (Y) I like person as you because I also make several changes or modifications in my hardware always with good results; trust me sincerely I'm happy with you guys :yes:

congrats and sorry Geeky1 welcome to Neowin (Y)