Bitcoin Forum

Anyone mining with the dual GPU 6870x2 cards? 

What kind of hash rates are you achieving?  What kind of power draw? 


By my rough math it seems like one could expect to easily achieve 600 MH/s+.  With the current prices, seems like a great alternative to the more expensive cards out there. 

There was a thread out there talking about these cards and I believe there were some issues with the drivers or some crap like that. However, I could be just pulling stuff out of my ass/foggy memory.

Given how you can buy these at Newegg with a 2 year warranty, depending on the MH/s and MH/w this could be a very interesting replacement for the HD 5970. Already running in to issues with 5970s with GPUs dying and looking to get off this train asap.

Sorry, found the thread. The issue was memory underclocking so your efficiency may not be as high as the HD 5970s due to only being able to underclock the memory 100MHz less than the core speed. Then again you get the revised 40nm die out of the 6870 so maybe it is a wash on efficiency..

https://bitcointalk.org/index.php?topic=35792.20

I may consider picking up a pair of these for giggles now that you've brought them to my attention and I see they dropped at the egg.

My 6870 works great at 1000 core, 300 memory for ~318-320 MHash/s. Actually getting down to 300MHz is a chore, I have to set it to 300 in Afterburner and then manually set the L1 to 300 using clocktweak. Underclocking the memory makes a pretty substantial drop in power though.

So pretty close to the hashing rate of a standard 5970 then.....nice. 

What kind of wattage are you using per card? 

I'd have to check my log book when I get home, but using a 650W Hale82 I believe load-idle is somewhere in the vicinity of 150W at the wall. It's pretty reasonable. I plan to run some comprehensive tests of the actual power draw of my cards over Easter, so I could give a better answer then.

Screw it, picked up a pair for cheap on some forums. Will have some numbers on this card next week.

Be sure to update the mining hardware comparison wiki, there are only single GPU 6870s listed there.

^^ Not to get off topic but how do you add to the Wiki page?  I take it you have to register with Wikipedia and then you can add in your info?

 :-[

For the wiki at https://en.bitcoin.it/wiki/Mining_hardware_comparison you just click the "Log in / create account" link in the top right of the page.

This seems pretty interesting.

7990 vs 7970 vs Kepler vs 6870x2 ???

My desktop that is sitting in my garage hashing away right now has a 6870x2, 6870, and a 5870. I have all of the 6870s set at 925/300 getting 295 mhs / core. They all run at 1.175v and I haven't been able to figure out how to adjust the voltage on them. I'm using 11.12 and Trixx to adjust the memory. Once I removed my wireless card that was directly above it and dropped the memory clocks the temps dropped around 12*c. My next goal is to acquire a 240v power meter and figure out how much power everything in my garage is pulling.

got my first two up and running......stable as hell @950/850.....temps well below 85 degrees.  getting just under 300 per core using cgminer.  At this price they are quitea deal per MH. 

Cool, what's the power usage approximately?

Just started playing with my 6870x2(one deal fell through). Right now at stock clocks(950 core, 1050 memory) the thing is blistering hot. GPU-Z is reporting some component around 95 Celsius, scary hot. At 100% fanspeed the cores are in the 70s with ambient temps around 20C. Going to run the card a bit and then work on dropping the memory clocks. Before I take power numbers I need to move it to a different rig.. it is sitting in my desktop with a high strung 2600K and 16GB of ram  ::) Just thought I'd update.

Hmm interesting card. I just found out about this dual 6870 card just now. It could be the next best high density card in terms of initial investment. Looks like it's better than a 5970 or 6990 price wise. But these reports of memory underclocking and temperatures do not look good.

Perhaps it has high temps because it doesn't have that reference-like design with centrifuge fans? I noticed that reference design cards with these centrifuge fans are louder, but they can direct air better.

Tried flashing the BIOS to set the memory to 500 MHz since I can't get Trixx or AfterBurner to drop the memory below 1000 MHz. That  didn't end well, Windows BSOD and Ubuntu refuses to display video. That being said I was able to drop the voltage with both AfterBurner and CGMiner. Dropping from 1.176 to 1.1v let the card mine at 950 MHz with no problems. Dropped the temps a bit and dropped power consumption at the wall by 40 watts(Corsair AX750 is feeding it). Going to flash back to the stock BIOS and worry about downclocking the ram later.

On mine I have it crossfired with another 6870. With crossfire enabled Trixx it will allow me to adjust memory, but not voltage. With crossfire disabled I can adjust voltage, but only change memory a set amount below core clock. Right now I have the card set to 950/300 on stock voltage and it pulls 295 MH/s / core.

PS: CGminer 2.3.1-2

EDIT: What were your power consumption numbers on the card alone?