Powercolor 7870 LE (Tahiti) - NEED HELP!

[AndrewK]

Ok guys. I'm setting up a rig for a buddy I work with and I'm about to throw the damn Powercolor cards out the window.

Specs:
A6-5300
Asrock extreme 6
4gb of ddr3
1000 watt OCZ gold
and 2 or 3 Powercolor 7870 tahitis

Problem:

No matter what settings I use I cannot get the cards to mine over 330kh/s. The cards are voltage locked so I can't adjust that. Stock clocks are 925 core and 1500 mem.

example cgminer .bat:

cgminer --scrypt -o http://litecoinpool.org:9332 -u x -p x --lookup-gap 2 --thread-concurrency 8192 -g 2 -I 13 -w 256

This is stable and gets me 330kh/s any intensities over 13 cause massive hardware errors

if I try:

cgminer --scrypt -o http://litecoinpool.org:9332 -u x -p x --lookup-gap 2 --thread-concurrency 16384 -g 1 -I 13 -w 256

cgminer won't start


basically nothing I try will get these cards to run... To boot, they artifact if turned up to the first setting listed above.


I've tried them on my test bench and get the same results. I tried reaper and got shutdowns, false starts at settings that would give good kh/s.


Should I just return all these cards? ( I have 4 of them)


Thanks for any help you can give.

[tacotime]

In afterburner, set core to 950 MHz and memory to 1555 MHz

use reaper and this litecoin.conf

Code:

host yourpool.com ### Do not add http://!!
port 8344
user username
pass password

protocol litecoin

worksize 256
vectors 1
aggression 20
threads_per_gpu 1
sharethreads 32
lookup_gap 2
gpu_thread_concurrency 18610

Tell me what you get

Try also aggression 18

[MKEGuy]

If you search the cgminer thread there is a setting you can enter in a CMD window.  setx GPU_MAX_ALLOC_PERCENT_100 or something similar.  Check there for the exact setting, you dont want to use something else.

That will fix the CGMiner not starting with higher thread concurrencys if you are using 11.3.

[crashoveride54902]

i'd return them...that 7970 powercolor i had...sent it to rma and the card they gave me back worked for a whole 4 days mining btc before it quit...just sent it out today for another rma...powercolor is just shit imho...hopefully 3rd times a charm with this company...good luck to you

[vdragon]

Since its a tahiti, try running 950/100 thread concurencies 24000 - these tahiti chis really dont have a pattern for ltc, every card is different

[AndrewK]

Thanks for the suggestions guys. Will try when I get home and update.

[ryantc]

Are you running 4 cards all together and each get 330Kh/s

I might be wrong, but if you are mining LTC with 4G of RAM and 4 7870 cards, it's not a good combination.

I personally use 3 powercolor 7950, the max -I is 13 higher than this will product massive HW......so I guess you don't need to bother this parameter

you don't need --thread-concurrency 8192, my cards all mining at 510Kh/s just fine without it.

so I can only conclude that increase your system RAM to 6 or 8G, and see if hashrate increases

[AndrewK]

No go on changing any options. Couldnt get cgminer to start with: setx GPU_MAX_ALLOC_PERCENT_100

Reaper crashes with intensity over 13 or so as well.

Deleting all options except -i 13 gave me about 300kh/s

Interestingly if I downclocked the core to 725mhz it increased the hash rate to 315kh/s... Downclocking memory had detrimental effect after hitting below 1400mhz


I initially tested 2 cards together on 1 board with 4gb of ram. (I run 3 5970s on the same type of board with only 4gb and get standard hash rates). I then tested only 1 card on the 4gb board. Then tested another card on a different board with 2gb... Got the same results.

I can't flash bios as RBE doesn't recognize any 7800 series bios... ATIwinflash won't let me flash either. I believe the bios is locked.... I'm just about through messing with these mother fuckers...

Gonna enjoy having to send them back to newegg. Hopefully they don't charge me a restocking fee.


Any other suggestions would be appreciated but at this point I don't think there is much else to try.

[AndrewK]

Should also mention I'm running 13.1 drivers... gonnna try the 13.3 beta drivers

[ryantc]

interesting, did you try to change -w to 128 or 64? and try to keep the core/memory ratio to about 0.7

[scifimike12]

This is the reason why I gave up litcoin mining couple months back.  Couldn't get my 7000 series cards anywhere near what some people reported, or close enough to what I get with bitcoin mining (550Mh/s ~ 550Kh/s).

[AndrewK]

I've tried 128...

I have a 7970 diamond mining at stock clocks and 520kh/s.... Its not a 7000 series problem... This is just a POS powercolor problem Lol.

Anyways, I flashed to the MYST bios and no luck. I'm gonna try and flash to a sapphire XT bios. If that doesn't work I'm gonna just chalk it up to Powercolor buying some of the most crappily binned tahiti cores it could find and then shipping the finished product to unsuspecting customers.

On a possibly related note, I did ran the GPU-z ASIC quality test on one of the cards and it got a 59%... Maybe its the high stock clock (925 core and 1500 mem)...

[tacotime]

Interestingly if I downclocked the core to 725mhz it increased the hash rate to 315kh/s... Downclocking memory had detrimental effect after hitting below 1400mhz

Try 725 MHz and 1500 MHz RAM, intensity 14, 16, and 18

There may just not be enough memory bandwidth for that many shaders

[AndrewK]

Nope, nope, and nope... Massive hardware errors when any intensity over 13 is tried no matter core or memory settings.

[KWH]

All my GPU's mine perfectly with a slight core OC, under clocked Memory and undervolted. Upping the Memory speed doesn't do anything but raise heat levels for me.
7970,6950,5850 and 6870's. I use cgminer.

[vdragon]

All my GPU's mine perfectly with a slight core OC, under clocked Memory and undervolted. Upping the Memory speed doesn't do anything but raise heat levels for me.
7970,6950,5850 and 6870's. I use cgminer.

 KWH we are talking about litecoin and scrypt here, not bitcoin.

[KWH]

All my GPU's mine perfectly with a slight core OC, under clocked Memory and undervolted. Upping the Memory speed doesn't do anything but raise heat levels for me.
7970,6950,5850 and 6870's. I use cgminer.

 KWH we are talking about litecoin and scrypt here, not bitcoin.

LTC is what I mine. Assume much?

[AndrewK]

Oh well... I have 3 of them mining away on a board for right this second. They are going back to Newegg on monday though. Wonder if they'll give me shit since I haven't game tested them?

[KWH]

Oh well... I have 3 of them mining away on a board for right this second. They are going back to Newegg on monday though. Wonder if they'll give me shit since I haven't game tested them?

I've yet to have an issue with returns to NE, always a first though. Good luck!

[crashoveride54902]

Oh well... I have 3 of them mining away on a board for right this second. They are going back to Newegg on monday though. Wonder if they'll give me shit since I haven't game tested them?

good choice