2x 7970 GHz edition won't go beyond 1125Mhz

[navidos]

Hi Folks,

I got the following setup recently up and running.

MotherBoard: Asus Sabertooth Z77
CPU: (Intel® Pentium® Processor G630T (3M Cache, 2.30 GHz
RAM: 1Gig DDR2
HDD: 120Gig SSD OCZ Agilty 3
Power Supply: 1000W ChiefTec
Graphic Cards:2x XFX Radeon HD 7970 GHz Edition 3GB GDDR5
OS: Windows 8 Professional 64Bit

GPU 0 =78-82 degree
GPU 1 = 65 degree

Avg MH/s = 675Mh/s

The thing is, my Ghz edition cards can go up to 1500Mhz GPU clock
but whenever i go beyond 1125 Mhz and try mining. I get driver error
and GPU is sick or dead in CGminer and GUIminer.

I had another setup with almost same HW but my 7970 cards are not Ghz
edition (XFX again) and their max is 1125 Mhz, and I get same result with them.

any suggestion would be nice.

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[notaek]

You are simply overclocking too high.  You can try boosting the voltage on the cards if you really wish to surpass the 1125MHz mark.

[crazyates]

Some cards can OC farther than others. Yours apparently top out around 1125MHz. This is to be expected.

I can guarantee you that those cards are NOT OCing to 1500MHz when they're not mining. Even the best cards usually top out around 1200MHz. You sure you're not looking at your memory clock?

[navidos]

Thanks for replies guys.

1125Mhz is the maximum for non Ghz edition 7970 cards.
for Ghz edition you can go up till 1500 which in my case never happend.
I put Memory clock on 300 but when mining starts it goes up automatically.
I saw other guys and sources which got 700Mh/s with 7970 cards but not sure
which card brand or clock.
any way, so what i understood is that i shouldn't expect them to work at those
clocks, right?
alos i'm not so familiar with voltage concept and how should I play with that
in OCing, I use catalyst which don't give me voltage option but other OC tools
has it.

Should I go after that? or there is nothing more left in my setup to be pulled out.

Thanks.

[navidos]

New funny thing, I get the exact same main board and card for my another rig
and it's denying to work even on 1125Mhz just standard 925Mhz is ok, otherwise
driver stopped working msg shows up.
It's now killing me why 2 exact same setup should act differently.

[crazyates]

I saw other guys and sources which got 700Mh/s with 7970 cards but not sure
which card brand or clock.

I have a Gigabyte 7970 GHz edition, and it comes with a stock voltage of 1.256V and stock clocks of 1100MHz. The high voltage allows me to go all the way up to 1200MHz, which gets me ~722MH/s at those clocks. Your XFX prolly has a lower stock voltage, so it can't OC as far.

[navidos]

I can use other softwares like riva tuner to get acces to voltage.
should I play with voltage when i'm doing OC?
which voltage should i choose if i'm gonna use 1200Mhz?

regards,

[navidos]

I saw other guys and sources which got 700Mh/s with 7970 cards but not sure
which card brand or clock.

I have a Gigabyte 7970 GHz edition, and it comes with a stock voltage of 1.256V and stock clocks of 1100MHz. The high voltage allows me to go all the way up to 1200MHz, which gets me ~722MH/s at those clocks. Your XFX prolly has a lower stock voltage, so it can't OC as far.

I also got another rig with 2x 7970 from Gigabyte. these cards gave me way less hassle (never changed them,xfx card changed 4 times )
tough the production quality of XFX seems to be higher grade but cooling is tougher while giga can easily use the external fan help for cooling.

I'm getting same frequency there as well, which SW and voltage are you using on them?

regards,