GTX 285 Matrix on LN2

I figured that I would start this thread for a few reasons: first, the result is decent and second, it was damned hard to get...

I recently purchased a 285 Matrix because I haven't really played around with the Nvidia 200 series much because I wasn't into subzero stuff when it was around (and I only had AMD/ATI at the time). So I got the card all prepped with liquid electrical tape, sourced the GTX 260 Lightning / 285 Matrix voltage tool (available here at Madshrimps).

I read a few results on HWBot looking for info on the card as well as reading Pieter's article. I dropped down to -100°C and set the card to 900 core. Throughout the bench I dropped the card down to find a CB/CBB. There didn't seem to be any cold bug, but once the benchmark finished and I was brought back to the desktop, it was artifacting like crazy at -190°C until the screen froze.

Since that didn't work out, I decided to try something more a bit more conservative. I set 1000 core with 1.40V. This passed without any issue right around -100°C. Next I raised core speed to 1025 with 1.45V and and lowered the temperature to -120°C. It made it through GT1 and during GT2 when the guys are on the elevator it froze for a second. After that, the colors were odd and the score was terrible. I tried a few more things but the one that ended up working was not letting the card get colder than -110°C. This passed flawlessly at 1025 core.

I tried a few other speed/voltage combinations. 1150 at 1.525V made it all the way to GT3 at -110°C. If I let it get colder, it would fail during GT2. If it made it through GT2, it would freeze in GT3 when she's walking in the room at the beginning (one time it froze right at the end of the bench).




So the point of all of this is that I still have no idea how to bench this card. It seems like there is some sort of cold slow that moves around (no idea how or why). I tried more voltage and less voltage and all kinds of different clocks but it pretty much seemed like luck when I got a good result.



Have any of you guys benched anything in the 200 series? Does this sound like anything you recognize? Mind helping a bit?

Just as an update, Gunslinger over at XS has suggested that the cold slow might be courtesy of the memory... so I'm going to try the GTX 480 trick and use a hair dryer to keep the memory warm.





Here's the good stuff (click for larger):

I'm trying to figure out how I'm going to keep the memory warm... i.e. how I'm going to route the hot air from the hairdryer.

I'm trying to avoid hardmodding this GPU as much as I can. I'm fine with hard mods on cheaper cards (like my 275), but these things are hard to find. I got really lucky finding one as easily as I did.

With that said, how does one figure out a vPLL mod? The vMem mod is already published in the madshrimps link above but I've never tried to determine a PMM volts mod. I don't even know what to look for... is there another controller with a simple FB mod?

Neat! I'll look into this in a bit... job applications now.