Better Cooling for the 7800GTX

So after playing FEAR at 90C for the first week of having my 7800GTX, I had had enough, and since I still had alot of 0.025" guage copper left over from the 6800Go in a D810 mod, I decided to put it to good use and do some modding .

The general problem with all heatsinks from the Dell laptops is that they all are designed to allow a little bit of room between the core and the heatsink. This is because Dell uses those aluminum TIM plates and not paste on their cards (easier when mass producing the cards). Anyway, apply a thick layer of AS5 might drop temps a bit from the stock aluminum plate, but it still doesn't get the job done completely. Taking my heatsink off my 7800GTX, I was surprised to find that there was still a bit of the core that had not made contact with the heatsink, despite the rather thick (comparitively) layer of AS5 I had put on the core. So, on to work. First, I cut out a square just the size of the core and sanded it down with 600grit to remove sharp edges as well remove any finish and oxidation. I then soaked the plate in 91% isoprophyl alcohol to finish the cleaning process:

(Reference picture of copper plate on 6800Go from D810 project)

Next I made a custom design heatsink for the RAM chips on the back of the card. The main problem I found with my initial overclocking and testing of the card is that the RAM has a TON of potential. The chips are coded GC16, which should label them as 1.6ns memory and make them capable of at least 625MHz (1250MHz effective), and I've had them at 1300MHz+ in a cold room. Anyway, they just that get waaaayyy too hot, and the dinky aluminum alloy back bracket isn't going to keep the back side cool enough to keep up with the better cooling of the front. So, here's what I came up with:

*audience gasps, oooos, and ahhhhs* Yes, yes, it's not pretty but it works. Clamped it down to a 1/4 board and used a jig saw to make the cuts. Only screw up happened when I drilled the hole and the bit nabbed the edge and pulled the copper plate up around the screw hole. I was able to bend it flat again (gotta love copper) but I still had that damn buckle on the lower center portion, bah .

Anyway, here are the parts laid out:

My original design was to use the stock X-frame bracket that comes with the other Dell cards (this one is from an X600) to secure the heatsink onto the core, and then epoxy the copper RAM heatsink onto the bottom RAM sinks. Here's one of the attempts:

Long story short, no go. I tried thermal epoxy and super glue, neither would secure the plate while still using AS5 as the main heat transferer. So, back to the drawing board . I was running out of steam (working on 4 hours of sleep from playing Serious Sam 2 with friends all night ), so I just used the original back bracket that came with the Go 7800GTX, which would hold the copper bracket to the RAM sinks. I just hoped that it wouldn't be too thick and start touching the mother board . So the cooling goes RAM chips>AS5>copper heatsink>thermal pads>original back bracket. Unfortunately it's too thick, but I jimmied the sucker in anyway . It fully sits in the slot on the motherboard, and only the lower portion (towards the thumbpad) is slightly pushed up higher by the copper heatsink. It doesnt touch the motherboard, looks like it's blocked by the south bridge, so there's some extra cooling there . Anyway, here's the finished product:

Looks great I think . I had to rebend some of the fins on the right side to allow more room for the card. Other than that, the first part was done, now the question, would it work? The answer: ohhhhhh yeaaaahhhh .

In my dining room where I usually work, it's about 80-85F (27-30C) because it's relatively close to the wood stove. The card used to idle at 48C, now it's sitting at 45C. Load temps used to reach 90-92C in F.E.A.R., now I havent seen them climb above 82C. I would say that's definitely substantial .

Next is to see how much higher I can overclock (stably), with a special focus on the RAM. I use F.E.A.R. to test my maximum stable clock, as it is the most intensive application I have. Right now my everyday, stable clock is 450/1180. Here's to hitting at least 1250 stably with the RAM .

Lol, thanks alot man, glad you like my work . Yah, I dunno, I just dont think that I got that great of a card. FEAR will actually run fine at 1250 and 1300 on the RAM. However, especially at 1300, I get these crazy snow in the shadows and transparent textures. I believe part of this is due to the multisampling AA I use for transparent textures, which puts more stress on the card, but a 91C operating environment will stress the hell out of any component. I just finished checking and testing this thing out and the heatsink definitely does work well. The copper fins get too hot to touch, so they're definitely doing their job . I need to get some sleep, but I'm hoping to do some flashing tomorrow and see how high and stable I can get this card. I'm actually pretty excited that the core temp is as low as it is, 460 core stable everyday would be a very nice performance boost .

drizek: Thought of attaching it to the heatpipe, but here's the problem: the heatsink still has to abide by the laws of thermodynamics . I could easily extend the heatsink upward at the end to attach to the heatpipe, the problem is that the heatpipe would most likely be hotter than the RAM sink and actually HEAT the RAM. Remember that the core still goes up to 75-80C. Although the RAM probably gets close, the air surrounding the heatsink is going to be MUCH cooler than the heatpipe. Judging that the HDD operates at case temp, and the RAM sink is directly next to the HDD, the HDD is now at 33C, and so should be the surround air. 33C is a pretty cold sink for a 75C+ RAM sink to diffuse into. Also remember that the fans are not sealed and that there is some airflow within the case. Since the card is so close to the fan housing, it definitely gets a breeze. Otherwise, I think the HDD would be operating at a much higher temp.

AS5 seems like a good idea too. Here's the problem with it though, I think you actually want to ISOLATE the heatpipes so that they carry all their heat to the heatsink in front of the fan. Again, the aluminum alloy heatsink that they're attached too might actually draw heat away from the heatpipe.

ZX81 - at 450/1180 I get ~7500 (give or take 30). It's true that the cards are rated to 100C+, however, the cooler you run a component, the more stable it becomes and the higher you can overclock it. Technically you can think of this on a quantum scale. The higher the temperature of operation, the more excited the atoms are and the more disordered they will become, specifically with the electrons jumping around all over the place. This makes a pretty bad system for a current to go through. You cool the chip, it becomes more stable because the overall energy within the system has been lowered and hence the disorder (entropy) has been lowered too. The card will not fail at it's stock clocks up to the specified temperature (well, it shouldnt), that's why it's rated as such. However, if you want to raise clocks, well then better cooling is in order .

hellstrider189 - I was thinking about doing something for the top heatsinks, maybe slipping another copper plate in there and having fins extend out the side, I still might attempt it later on. While the aluminum alloy heatsink isn't the best cool material, it still does cool the RAM chips. I was thinking about cutting it, but I'm afraid that it's too delicate and it will break under the stress .

And thanks guys, I was nervous as hell when I was doing it too, thought I might have to go on high blood pressure meds . If you attempt it just make sure you measure exactly and make sure that no copper is touching any components

Just did some F.E.A.R. testing, the card definitely runs alot better. Even in this damn hot room (82F atm), it never went over 82C. The core still wont go stably over 450MHz, but the artifacting over it is much less, I think it needs more power. The RAM however, wow what a difference. I was running it at 450/1300 for awhile and there were only minor artifacts. 1280 and 1270 were almost nonexistant. I'll keep it at 1250 for now, which is a definite improvement over the 1180 I had before. I think the next step is to get some airflow through the case, as the other components are noticably hotter. The HDD went up to 38C, and the DIMM temp was hitting 51C, so I took the little door off the bottom of my laptop. I might put a copper door down there or something to help with heat transfer. I was also thinking of installing a fan by the PCMIA slot above the HDD. I already removed the blank that Dell inserts and that helped out a bit. Anyway, we shall see

Hmmm. maybe, maybe not Lemme get back to you on that .

And simply, I didnt get into computers until my 16th birthday, before then I didnt even know what a motherboard was. I actually had a tech put a video card in for me because I didnt know how to do it (this was on a desktop mind you). Right now I'm 18 1/2. You can learn quickly, just read around online and soak up all the info you can and try to do something with it

I'm getting my kicks now because that's going to be me in 8 years . Pre-med at Boston University .

I was thinking of volt modding, but she runs hot enough already and I can play every game I own maxed out. The other thing that worries me is that the HDD gets up to 41C in FEAR because the heatsink is so close to it now. I think I'll have to open her up one more time and thermally isolate the HDD somehow.

lmfao 8bit, I dunno, I've always been into tweaking, maybe it's because I played with legos so much as a kid