Overclocking a 4850

[spittledip]

Hey,

I have a 4850 1 gig (HD-485X-ZDFC) that I am currently working on getting a good OC for. I was upping the GPU clocks and testing in Furmark for artifacts. After getting it to 726 mghtz I decided to test with BFBC2 and FRAPs it to see how it would perform. Played for about 20 mins or so with no problems. I then decided to test in 3Dmark06- about 30 seconds into the first test, the screen went blank. I assumed it crashed so I hard rebooted, but as the machine was going down Windows logoff popped up oin the screen so I figured the Video card had failed to send a signal to the monitor. I tested again in 3Dmark06 at 710 mghtz- during the last test the screen went blank again. I waited it out and the screen came back on when the test completed. Temps were at their height around 65C in 3Dmark (they were higher in furmark)

My thought was that this must be a power issue and that perhaps I needed to up the voltage. I decided to dump the BIOS and edit it to up the voltage that way. Upon opening the BIOS dump with the editor, I discovered that the card was already set to the highest voltage in the drop down box- 1.258 . There were no other options to choose from. This is my first edit of a BIOS, so I am not sure if I can up the voltage by entering another figure in there (say, 1.3 or so) b/c the instructions indicate that this might not be a good idea.



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At any rate, I am open to suggestions as to how to proceed at this point. Is ther another possible issue? Also, are these cards supposed to be lower binned 4870s, or is it another 4850 1 gig?

system:

XP 32 bit
q9550 @ 3.4 1.168v
ZALMAN ZM750-HP 750W

Thanks for any suggestions.

 

[spittledip]

No one has any ideas? Would doing a voltmod be the only answer? Is this definitely a power issue?

 

[spittledip]

90 views and no help?

 

[GaiaHunter]

Does your card crash in actual games?

 

[nemesismk2]

Have you tried downloading 3DMark06_v120_1901.exe or the patch?

http://www.futuremark.com/benchmarks/3dmark06/download/

 

[kalrith]

FWIW, I recently purchased a 4870 and used GPUTool to test for artifacts and find my max overclock. Furmark is great for stability testing, but AFAIK it doesn't check for artifacts.

I'd recommend the following:

1. Set GPU to stock clocks
2. Use GPUTool to find max core clock
3. Set GPU to stock clocks
4. Use GPUTool to find max mem clock
5. Set core and mem speeds to 98% of max
6. Test for artifacts with GPUTool in full-screen mode

That's what I did. I got a max core clock of 836 and max mem clock of 1065. I run the card at 820/1050 with no problems whatsoever. I use ATI Tray Tools to overclock the card at startup. If step 6 finds artifacts, then I'd recommend backing off the mem speeds a bit rather than the core speeds, since the latter make a bigger difference in gaming performance.

BTW, be sure to monitor your temps while torture testing. I have a Scythe Musashi on mine, so the temps never get above 65°; however, I've heard of a lot of overheating 48xx cards.

I'd also recommend running GPU-Z to make sure your card is in PCIe x16 mode. Mine was improperly seated and was running in x1 mode.

Edit: AFAIK, there aren't any 4850s that are 4870s in disguise.

 

[spittledip]

Does your card crash in actual games?

I didnt have time to check really. It didnt for the time tests I took it through. Good point.

 

[spittledip]

Have you tried downloading 3DMark06_v120_1901.exe or the patch?

http://www.futuremark.com/benchmarks/3dmark06/download/

Thanks, will do so when I get home.

 

[spittledip]

FWIW, I recently purchased a 4870 and used GPUTool to test for artifacts and find my max overclock. Furmark is great for stability testing, but AFAIK it doesn't check for artifacts.

I'd recommend the following:

1. Set GPU to stock clocks
2. Use GPUTool to find max core clock
3. Set GPU to stock clocks
4. Use GPUTool to find max mem clock
5. Set core and mem speeds to 98% of max
6. Test for artifacts with GPUTool in full-screen mode

That's what I did. I got a max core clock of 836 and max mem clock of 1065. I run the card at 820/1050 with no problems whatsoever. I use ATI Tray Tools to overclock the card at startup. If step 6 finds artifacts, then I'd recommend backing off the mem speeds a bit rather than the core speeds, since the latter make a bigger difference in gaming performance.

BTW, be sure to monitor your temps while torture testing. I have a Scythe Musashi on mine, so the temps never get above 65°; however, I've heard of a lot of overheating 48xx cards.

I'd also recommend running GPU-Z to make sure your card is in PCIe x16 mode. Mine was improperly seated and was running in x1 mode.

Edit: AFAIK, there aren't any 4850s that are 4870s in disguise.

Thanks. I wasn't planning on messing with the mem speeds.


The temps only get to about 65 C or so OC'd- the card has the 2 slot heatsink/fan external blower so that keeps it pretty cool. I did notice it was running in 16x mode yesterday.

Gah, I keep on forgetting to install ATI Tray tools instead of ATItools. I will try that GPU tool also.


Thanks everybody for the input! Hopefully it is just 3Dmark that is the issue as was suggested.