Sapphire 7950 4L locked at ~520 kh/s

[Roflmcsupsup]

I have been discussing with multiple people an issue with the Sapphire 7950 4L listed
http://www.newegg.com/Product/Product.aspx?Item=N82E16814202030

It is seemingly impossible to get more then 520-530 kh/s with this specific 7950. This value does not change based on over or underclocking, using Reaper or CGIminer be it standalone or with GUIminer-Scrypt. The card has also been noted to reach it's OC speed and then fluctuate rapidly to some stock speed of 850/1200 in line with activity fluctuating from 99% to 60%.

Has anyone else noted this with their card? I have tried many thread concurrencies, worksizes, aggressions, voltages, OC's, OCing programs, mining programs, different pools, stratum. None of these have resulted in the card pushing past this amount.

I am considering flashing the BIOS as a last option unless someone has a different experience.

[Roflmcsupsup]

Based on this thread
http://www.overclock.net/t/1378557/sapphire-100352-4l-and-21196-00-20ghd-7950-the-final-holy-grail-of-hd7950s/

I think someone is considering the possibility of bios flashing the 7950 to a 7970. This could unlock additional shaders. Good to see if it works.

[superfastkyle]

I'm having issues with my 7950 as well. If its like mine it will not overclock unless you raise the powertune or board limit. If you do it runs extremely hot at 1.25v. It almost seems as this was intentional to make the 7970 alot better than this one. I have tried the gigabyte 7970 bios on mine and it has helped slighty

[Roflmcsupsup]

I resolved this issue.

The previous issue seemed to be caused by the voltage being limited and the clock would have issues constantly attempting to downclock to 850/1250 (for me at least) to compensate for the low voltage.

If you turn up the "Power control settings" in CCC you can lock in a higher OC.

Using +5% Power control Settings, 1055 GPU/1575 MEM and a higher fan speed I was able to get the card to do 600+ KH/s via cgminer

Thread Concurrency 16384
Worksize 256
Intensity 19
Vectors 1
GPU Threads 1

This was for the SAPPHIRE 100352-4L Radeon HD 7950
http://www.newegg.com/Product/Product.aspx?Item=N82E16814202030

I really enjoy the reference cooler design for being able to push all the heat out of the case but the noise is really unbearable above 45%.

[ryancs9]

had this same issue worst part is i couldn't lower the 1.25 vddc in linux

my solution :

flashed this bios http://www.techpowerup.com/vgabios/114183/ATI.HD7950.3072.120116.html

now i can push them up to 600k and with stock vddc of 1.09 temps run 73deg all day, every day

[Roflmcsupsup]

Thanks for linking to the BIOS, just to confirm you flashed that bios on the 4L?

[ryancs9]

yep works

 they have a bios switch so no big deal just back up your original