Better Cooling for the 7800GTX - Page 3

Post has been edited, I'm a little more than ornery when dealing with morons and I haven't slept yet . I dont care so much about rep as I do about people bashing my work, but whatever, moving on .

rally, exactly what I was thinking, that's why I'm staying with medicine.

Wooo, more tweakage! I consider the card pretty much hardware tweaked to the max, so now I'm fooling around with the software. First thing I wanted to do is test out the card completely, so I did some unplugged gaming. To my surprise, the card still handled FEAR pretty well, and even better, it only maxed out at 58C . Now I know I said I wouldnt get into overvolting because I dont need a cap to burst midway through the semester . However, I think undervolting might have some very nifty potential. I opened up NiBiTor v2.6 and checked out my BIOS. So it seems the card runs at 1.1V idle, 1.1V lower power 3D, and 1.3V at full power. I'm still testing, but right now I have my idle at 1V, my low power at 1.1Vand the clocks up from 250/658 to 300/750, and high power 3D down to 1.27V. Now I had to lower my overclock from 450/1200 to 440/1200 as there simply wasn't enough power available to run those clocks. I would get slight GPU miscalculations and a little snow every once and awhile, so I lowered them to be on the safe side. The benefit of all this? The card loads at 76C . I'll have to get down to the living room and next to the woodstove to see its true potential, but I'm very please with the reults, seems like its about a 4-5C drop in temps for a lousy .03v . Ran 3DMark05 and got 7405, which seems to be right on the money as far as performance goes, so I dont think the card is erroring at all. 1V at idle dropped my idle temps about ~1C, dont think it's really worth going lower and risking instability. I'm pleased with battery performance now, 300/750 still yields great performance in games while still giving some battery life. I might try tweaking this area later on .

NiBiTor is a BIOS editing program, so it requires you to flash the edited BIOS. I dont think there's anyway to really modify your 7800GTX without doing a BIOS flash. Anyway, it'd not really worth it unless you stay at stock speeds, I would have to say my original estimate was a little to optimistic . Seems that the temp only dropped maybe 1C-2C at most, nothing more. I'd rather keep my clocks, 83C load right now still isn't that bad I dont think.

.748v due to the way my volt-mod is configured, probably could go lower

Not really worth the upgrade, unless the CPU was free. A 1.6 @ 2.13 is the lowest I'd go.

Ah, well, you can't beat the price of free . My 2.4GHz only loads at 50C, maybe 52C at max in a hot room. But 2.4GHz over a 1.73GHz is a 660MHz jump in CPU, probably accounts for 200-300pts of that difference. Also, make sure you have your drivers on high performance and your windows XP install is tweaked and clean .

Just a quick update. First, for those who want to try out the cooling mods, here's a quick cross section I made with my awesome MS Paint skillz


Note that the copper shim mod helps the most, but the RAM sink definitely does its job for those that want to go further. The design allows the usage of the original back bracket to keep the card together so that no adhesive is needed .

I also wanted to update about some software tweaking that I'm doing, specifically undervolting. Stock volts on the Go 7800GTX are 1.1v 2D, 1.1V low power 3D, and finally 1.3v high power 3D. Right now I'm testing at .9v idle, which gives me about 15 minutes more battery life anyway. I also raised my low power 3D clocks from 250/658 to 300/800. The card was still perfectly stable at 1.1v with these clocks, so I think that I'm going to keep them. Anyway, I'll keep testing the voltage and see if this thing BSOD's or not. I'm not going to overvolt though, as this laptop is my bread and butter at school and I cannot afford to blow a cap and lose the laptop. That and I dont want to use the crappy X600 I have lying a round as back up .

Ahh, why didnt you ask before tana . Here's my closest guess without pulling it off the card (reconstructed it from the scrap copper). The actual copper plate that I used was a 4" wide, 10" long, with a thickness of 0.025". I think that's ~22 gauge if you go by wire gauge. It was sold as hobbyist's sheet metal and was the only size of copper sheet metal that my local hardware store carried (lucky me ). Off hand I'd say this is the thickest to go, but it definitely does the trick . The copper piece that I used on my core I just eye-balled. Judging by the rest of the strip left that I cut, I'd say it was 21mm square, but anything 20-22mm square would work fine I think. As far as the the actual plate goes, here's a blueprint displaying some more of my photoediting "skillz" (used GIMP on the text ):

A few things to note. First, the picture isn't directly to scale because it's not a direct overhead shot, but it's the best picture of my 7800GTX that I have. The dimensions are pretty accurate, and the tilde (~) signifies that my cutting was off with a tolerance of +/- 1mm at the most. The X is the mark where I drilled through the heatsink so that the fourth screw could connect to the motherboard. Even so, I can't tighten the screw all the way or it will press the heatsink against the PCB and components. However, leaving it ~1mm unscrewed does add extra support for that lone corner, so maybe it's a good idea to keep it in the design. The bottom half row you cut into where the chips end, and bend up and down alternately right where the chips end. The vertical side you have to bend up about 1/2 to 2/3 out to allow room for the Go 7800GTX's PCB. I've found it best to bend up and down alternately, but on those that you bend down, bend the entire fin slightly up, and those that you bend up, keep it straight. This makes sure that the fins do not touch any video card or motherboard components. EDIT: A final note is that you must cut the heatsink so that it stops before the connector to the motherboard (which is right under the "PUSH HERE"), and that it must stop before reaching the upper screw. Hope that helped guys!

Don, is your card stable at such low volts and clocks? Amazing that you didnt get anything out of it.

destruya, that copper plate is on the UNDERside of the card. The heat under the card needs to be dispersed to the environment, and the thin aluminum alloy plate that was on the RAM chips before in no way did the job adequately: it didnt conduct heat very well and what more, it kept it underneath the card instead of having fins to send it out to the sides. I was toying with the idea of putting another, small model on the upper heatsink, but I dont think I can fit it in. You must remember that the heatpipe assemble basically cools the GPU core and the core alone, the aluminum alloy heatsink does a horrible job of conducting heat (relatively).

Volts are the best friends you can have . In all seriousness though, I live in the middle of nowhere and it's a good 30 minute drive for me to see any of my friends, so I usually have my days to myself, as I'm not working this vacation. The other problem is though that they all went back to college and I'm still stuck here, down side of having a long winter break .