This is why the 8800 stock cooler sucks.

[YMAA]

I took my 8800GTX apart today to do a washer mod to the mounting screws. The basic idea is that it increases the force on the spring, which then in turn forces the screw head to push down harder on the PCB, and the PCB has nowhere to go but into the cooler. Seems to help a little, though I had to use thicker rubber washers because the hardware store I went to didn't have nylon ones. I did a similar mod not too long ago to increase mounting pressure on the Ultima-90...got rid of that annoying ability to twist the cooler even when screwed in all the way

But when I took the stock cooler off, this is what I found:



I had used AS5 on the core, and Ceramique on the RAM and shader processor the last time I took the card apart. You can see that the RAM and VRMs got next to no pressure from the cooler, while the core got decent contact. You can't see it in the picture, but the shader processor (the green chip with the exposed die on the left part of the card in the first picture) got decent contact as well.

If the part of the heatsink cooling the RAM was making decent contact the TIM would have been flattened like it was on the core and shader, but as you can see it wasn't. Could explain the high temperatures.

This shows how crappy the design of the stock cooler really is...I'm getting an HR-03 Plus as soon as I can. I'm guessing it's a similar problem for the 8800Ultra and 8800GT/S as well.

[Sailer]

So you're trying to say that the quality control was less than perfect? OK, this probably explains why my 8800 GTS runs hot as well.

You mention your Ultima 90 and how it twists around even screwed down all the way. I have the same trouble with my TRUE. I've had it on and off three times trying to get better contact, even tried bending the mounting clip a bit to put more pressure against the motherboard and the CPU, but it still twists every time I touch it. I wonder at times how much better the cooling would be with a good, solid mounting. Maybe it wouldn't change, but I don't know. I also wonder about who designed the two piece scissor type mount for the thing. It just can't hold as well as a solid mount would.

[MeltDown]

Originally Posted by YMAA

I had used AS5 on the core, and Ceramique on the RAM and shader processor the last time I took the card apart.

The shader processor?
Do you mean the nVIO chip?

Originally Posted by Sailer

So you're trying to say that the quality control was less than perfect? OK, this probably explains why my 8800 GTS runs hot as well.

Remember that YMAA has mounted and unmounted his stock HSF a couple times. I have never been able to get great contact after putting the stock cooler back on my 8800 Ultra either, although it runs no hotter than it did from the factory. So maybe it's not a QC issue so much as a bad design.

Originally Posted by Sailer

I also wonder about who designed the two piece scissor type mount for the thing. It just can't hold as well as a solid mount would.

The problem is that the heatpipes make it difficult to impossible to get a solid mounting plate in there. The regular Ultra 120 used a solid mount as I recall but it didn't have the extra 2 heatpipes (the ones that go straight up out of the base instead of rising at an angle first).

[YMAA]

Originally Posted by Sailer

So you're trying to say that the quality control was less than perfect? OK, this probably explains why my 8800 GTS runs hot as well.

I'm saying it's the way the cooler is designed. If I had to guess, the cooler is designed this way because of the thermal pads they use, not the thermal compound we use. Thermal pads are probably a lot easier than thermal paste for machinery to apply consistently to a lot of cards. So the reference 8800 cooler is designed to make contact with a thick thermal pad rather than a thin layer of paste.

Originally Posted by Sailer

You mention your Ultima 90 and how it twists around even screwed down all the way. I have the same trouble with my TRUE. I've had it on and off three times trying to get better contact, even tried bending the mounting clip a bit to put more pressure against the motherboard and the CPU, but it still twists every time I touch it. I wonder at times how much better the cooling would be with a good, solid mounting. Maybe it wouldn't change, but I don't know. I also wonder about who designed the two piece scissor type mount for the thing. It just can't hold as well as a solid mount would.

Have to give credit to Sirrobin4ever for this mod. You know the two mounting brackets that screw into the holes in the motherboard? The screws that force the mounting plate down on the base of the cooler screw into them. The screws have springs on them that take the screw head and push down on that holding plate. The mod involves those springs.

This mod is dead-simple. Take two fairly thin metal washers and place them on both screws so they're touching the spring. Put the hold-down plate on the base of the cooler as usual, so the holes on the plate will line up with the holes on the mounting brackets, as per usual.

Then screw in both screws, making sure the washer sits between the hold-down plate and the springs. Make sure you twist each screw evenly, so the force gets distributed evenly.

As the screws get in farther, you'll notice that there's a lot more resistance to them. This means you're getting insane mounting pressure on the IHS. You probably won't be able to put the screws in all the way, just go as far as the amount of pressure you want on the CPU (they can take well over 100lbs of force, so don't worry about crushing it).

I'll post up a picture of what it looks like next time I open up the computer.

[flasher702]

kudos for the excellent post YMAA. Short, sweet, and topical with a good pic

[Sailer]

Originally Posted by MeltDown

The problem is that the heatpipes make it difficult to impossible to get a solid mounting plate in there. The regular Ultra 120 used a solid mount as I recall but it didn't have the extra 2 heatpipes (the ones that go straight up out of the base instead of rising at an angle first).

I looked through the Anandtech articles and saw this design mount that appears to have been used at first.

AnandTech: Thermalright Ultra 120 Extreme: Is More Better?

As the article points out, it had to be bent slightly to get it in place. I'm handy with tools, as the article states, so could have managed it. A later Anandtech article notes both the present design and its problem, but notes that the design still needs to be improved.

AnandTech: UPDATE: Thermalright Ultra-120 eXtreme - Retail

I've been tempted to buy one of the original style mounts and give it a try, but haven't done it yet. As it is, almost every time I work on something in the case, I bump the heatsink and move it a bit, causing me to wonder how well the thermal paste is maintaining contact and good heat transfer.

[Sailer]

Originally Posted by YMAA

This mod is dead-simple. Take two fairly thin metal washers and place them on both screws so they're touching the spring. Put the hold-down plate on the base of the cooler as usual, so the holes on the plate will line up with the holes on the mounting brackets, as per usual.

Then screw in both screws, making sure the washer sits between the hold-down plate and the springs. Make sure you twist each screw evenly, so the force gets distributed evenly.

As the screws get in farther, you'll notice that there's a lot more resistance to them. This means you're getting insane mounting pressure on the IHS. You probably won't be able to put the screws in all the way, just go as far as the amount of pressure you want on the CPU (they can take well over 100lbs of force, so don't worry about crushing it).

I'll post up a picture of what it looks like next time I open up the computer.

OK, I may be a bit dense this morning, but if I understand you correctly, I can take one screw out at a time (thus leaving the heatsink relatively secure to the motherboard), put two thin washers over the end of the screw, and then put the screw back in place, thus increasing the pressure. Then I repeat this until all four screws have been modified.

Does that sound correct?

[tool_462]

My temps are fine with fan running at 60% full load, so I'm happy with it

Loudest thing in my rig is still my MCP655.

[MeltDown]

Originally Posted by tool_462

My temps are fine with fan running at 60% full load, so I'm happy with it

Loudest thing in my rig is still my MCP655.

You don't have an 8800GTX do you?

[tool_462]

Originally Posted by MeltDown

You don't have an 8800GTX do you?

No. If it was specifically talking about the 8800GTX then why are people talking about 8800GT/S/Ultra?

[MeltDown]

The Ultra is essentially an 8800GTX. The fan is different but the heatsink is the same (I could take photos that look just like YMAA's since the fan is not in those pics). I'll concede your point on why you were talking about the 8800GT, but all the other cards being discussed were G80s.

[tool_462]

G80, G92, G4 Tech TV, G-String. Who can keep it all straight.

[1Tanker]

Originally Posted by tool_462

G80, G92, G4 Tech TV, G-String. Who can keep it all straight.

G-String straight?? Makes for one awesome camel-toe.

[tool_462]

Originally Posted by Clue69Less

G-String straight?? Makes for one awesome camel-toe.

Fixed.

[1Tanker]

Originally Posted by tool_462

Fixed.

His reputation precedes him.