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Posted: Fri Jan 04, 2008 7:59 am Post subject: Overclocking Radeon HD3870

So this is my first time attempting to overclock anything. I have a Sapphire Radeon HD3870 256-bit interface, 512 Megs of DDR4 ram. Core clock is 777mhz, mem clock is 1126 mhz.

So I played with ATI Overdrive a bit and bumped things up here and there, but the fan speed was limited and it would shut down when I started WoW up. So on JAE's suggestion I got ATI Tray Tools and tried that, but unfortunately, it couldn't adjust the fan speed, said hardware wasn't supported. So I downloaded RivaTuner, and it can adjust the speed.

So I was playing with things last night. From my understanding the way to go is to overclock the memory first, then the actual GPU. So I started bumping the memory up 5 mhz at a time, and would run rthdribl for a few minutes each time looking for artifacts. Once I got some artifacts, I backed the memory clock off 10mhz, then started adjusting the GPU in 5mhz increments.

So stock it's 777mhz on the GPU, I had it up to I think 820 and when I went to 825 it went to a blank screen, which I assume is GPU recovery, it did that before when I was playing with the clock settings. When I launched WoW after about a minute it blank screened, I just restarted and it was back to stock speeds again.

Well, this particular time, after a reboot it would just keep blank screening over and over again. I ended up having to start windows in VGA mode at 640x480 resolution and then kill Catalyst Control Center and then bump my res back up to 1680x1050. But I couldn't get back into CCC to lower the clock settings, everytime I would try to start it, it would blank screen again. I tried repairing control center, that did nothing. Ended up having to uninstall completely and then reinstall.

So a couple of questions.... #1 Is my method of overclocking going about things the right way? #2 is there anyway to manually set the clock speeds so that if something like this happens again I don't have to uninstall/reinstall to fix it? #3 From what I'm reading it's normal for the card to idle at about 60 degrees C and go up to 90 or so underload. That's what it was doing with no overclock. With an overclock is that still a good temperature range? I think before it locked up last night, with RivaTuner kicking up the fan speeds it was idle at about 45 degrees, and about 75/80 under load.

Posted: Fri Jan 04, 2008 12:36 pm Post subject:

I've never used ATI Tray but ATI Tool will find the max for the core and memory and stress test it sort of.
I always back it off slightly and then you can save it as a profile and easily switch between stock default settings and your overclock setting.
http://www.techpowerup.com/atitool/

Posted: Fri Jan 04, 2008 2:21 pm Post subject:

Serious Tom wrote:
I've never used ATI Tray but ATI Tool will find the max for the core and memory and stress test it sort of.
I always back it off slightly and then you can save it as a profile and easily switch between stock default settings and your overclock setting.
http://www.techpowerup.com/atitool/

I don't think theres really any need for profiles with this one. Whenever there is no load on the GPU it automatically goes to the lowest possible settings. I think it's 300 mhz GPU, and 1125 mhz memory. Then when you put load on it, it will jump to whatever you had the clocks set to.

I took a little more time today and ran the fan on it a bit hard while I was testing. Seems 360 mhz is the max for the GPU, any higher and it just blanks out no matter what the memory clock is. But it's never getting above 60 degrees C even under full load. I was able to bump the memory clock all the way to the max, 1387 mhz. It ran rthdribl beautifully like that at upwards of 350-400 FPS with no artifacts at all, and temp at max load was only 65 degrees.

But when I started up WoW I was getting screen tearing and artifacts out the wazoo, had to drop the memory clock down to 1301 mhz to get those to go away, and it seems happy at that setting. Then I was able to drop the fan speed down to where it's not much louder than it is at idle and temps still don't get above 65 degrees, so I guess I will leave it like that and be happy.