A "wall" on a 3870 card?

[Dougx1317]

Now that I've resolved my heat problem, I feel that I should be able to get more out of my card. I have a Sapphire 3870 GDDR3 512MB running at 835Mhz/2000Mhz. Overclocking has increased my performance, but I seem to have hit a wall. I can get the core up to almost 860Mhz without artifacts or high temps, yet my performance is the same as it is at 835Mhz. Why is this? I can't get the memory any higher. Is there something I'm not seeing here?

 

[jedimasterben]

Well, it's just that a higher clock speed doesn't necessarily make more performance. Something else in the card is not able to keep up and the performance will stay the same. It's just what happens. I'd clock it down to where the performance stops rising to cut the power requirements.

 

[Dougx1317]

After opening RivaTuner's monitoring, I've realized that the clock never goes above 823Mhz. This seems to be the limit no matter where I set it. This would explain the wall I'm hitting, but why is this? The temp is never above 65C and there is no artifacting. What would cause this?

 

[Aneesh@4GHz]

Core oc will not increase performance,OC Memory to increase performance on games!

 

[Dougx1317]

Well, I can't get my memory above 1050Mhz without artifacting. (Remember this is the GDDR3 version.) Is there anyway to increase the voltage on the VRAM? Or is there another way?

 

[closed_deal]

This www.sharkyextreme.com/hardware/videocards/article.php/3211_3746916__9 review mentions using RivaTuner with success :

Quote:

The Gigabyte Radeon HD 3870 512MB offers a specialized version of the GDDR3 model, with a custom cooling solution and Ultra Durable 2 components, so we were very interested in how the card would overclock. The default clocks as measured by the ATI Catalyst Information Center and OverDrive tabs were 780 MHz core and 1900 MHz GDDR3 memory.

OverDrive's automatic tuning mechanism resulted in an overclock at 870 MHz core and 2080 MHz memory speeds, which represents an approximate 12% jump to the core speed and almost a 10% increase in the memory clock. We were able to take the card to the limits of OverDrive (880 MHz core/2100 MHz memory), but subsequent testing in RivaTuner showed this to be extremely close to its limit for a 100% stable overclock.

Keep in mind that this overclocking data is based on one card, and as with most things in life, your mileage can definitely vary.

*This is info i know works for the GDDR4 version:*

There is the 3870 Update BIOS v010.071 knocking around, that'll help you overcome the wall you generally hit at 865mhz core. Also you can volt mod the 3870 though there are no voltage soft mods as the voltage regulators are fixed.

I used winflash to do may cards, though there are others. Make sure you read the instructions fully and make a backup of your current 3870 BIOS.

Although my cards in crossfire don't hit above my sigs spec's, i have overclocked one of them (on water mind..) to 940Mhz core max run and 900Mhz core (Furmark stable) on stock voltage .

It is a risk to flash your BIOS, but it's your decision if you try it .

 

[Dougx1317]

I have the Sapphire GDDR3 3870, so it won't be able to overclock the VRAM as high. I have bios Version 10.080... I've been using Rivatuner, but as I said the VRAM can't work over 2100Mhz. This may be normal for GDDR3?