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Title: Raising the clock reduces hash rate? Post by: TripHammer on July 29, 2011, 03:26:01 AM Hi,
I have a new XFX 6970 running on Win 7 x64 with the 11.6 drivers and 2.4 SDK, I'm using guiminer with Phoenix and the following: -k phatk VECTORS BFI_INT AGGRESSION=11 WORKSIZE=128 FASTLOOP=false I've over clocked to 975/700 with 1.2v using Trixx I get about ~406 to ~411 MH/s If I raise the core clock to 980 MH drops to ~400 If I raise the core clock to 985 MH drops to ~250! ??? If I go above 985 I get a freeze, I understand that :) Can anyone explain why? Thanks Trip Title: Re: Raising the clock reduces hash rate? Post by: IlbiStarz on July 29, 2011, 10:53:50 AM Not enough power maybe?
Title: Re: Raising the clock reduces hash rate? Post by: jrtubs on July 29, 2011, 03:13:20 PM Your Voltage will need to be raised.
https://en.bitcoin.it/wiki/Mining_hardware_comparison this should show you what people are getting at what overclock and also show u what kinda voltage people are using. Title: Re: Raising the clock reduces hash rate? Post by: TripHammer on July 30, 2011, 01:37:55 AM Yup thanks guys, I've been over those pages many times, I took the v all the way up to almost 1.3 and still no go, I've got it stabalised at ~413 now so I'm happy
Title: Re: Raising the clock reduces hash rate? Post by: JoelKatz on July 30, 2011, 01:46:08 AM Can anyone explain why? Thermal throttling.Title: Re: Raising the clock reduces hash rate? Post by: hmblm1245 on August 01, 2011, 01:16:38 PM I too have noticed the same with XFX 6959s. i have a 1000w psu and 1 xfx 6950. When i push them higher than 900mhz the mhash drops. I am also happy with the mhash so i dont worry too much about it.
Title: Re: Raising the clock reduces hash rate? Post by: Jack of Diamonds on August 01, 2011, 10:44:38 PM I too have noticed the same with XFX 6959s. i have a 1000w psu and 1 xfx 6950. When i push them higher than 900mhz the mhash drops. I am also happy with the mhash so i dont worry too much about it. Did you set Powertune to +20 in CCC before overclocking? The hashrate only drops if it's at 0, it attempts to lower power usage to conserve power Title: Re: Raising the clock reduces hash rate? Post by: hmblm1245 on August 02, 2011, 01:58:58 PM No i did not and Yes that is the reason i cannot go further. Thanks i can get a bit more outta my machine.
Title: Re: Raising the clock reduces hash rate? Post by: Trini8ed on August 15, 2011, 05:57:24 AM Hi, I have a new XFX 6970 running on Win 7 x64 with the 11.6 drivers and 2.4 SDK, I'm using guiminer with Phoenix and the following: -k phatk VECTORS BFI_INT AGGRESSION=11 WORKSIZE=128 FASTLOOP=false I've over clocked to 975/700 with 1.2v using Trixx I get about ~406 to ~411 MH/s If I raise the core clock to 980 MH drops to ~400 If I raise the core clock to 985 MH drops to ~250! ??? If I go above 985 I get a freeze, I understand that :) Can anyone explain why? Thanks Trip This is what happens when you change the clock it changes this make sure its +20% http://dl.dropbox.com/u/13699180/AMD-Overdrive-POWER.png Title: Re: Raising the clock reduces hash rate? Post by: pixilated8 on August 18, 2011, 02:26:38 AM Hi, I have a new XFX 6970 running on Win 7 x64 with the 11.6 drivers and 2.4 SDK, I'm using guiminer with Phoenix and the following: -k phatk VECTORS BFI_INT AGGRESSION=11 WORKSIZE=128 FASTLOOP=false I've over clocked to 975/700 with 1.2v using Trixx I get about ~406 to ~411 MH/s If I raise the core clock to 980 MH drops to ~400 If I raise the core clock to 985 MH drops to ~250! ??? If I go above 985 I get a freeze, I understand that :) Can anyone explain why? Thanks Trip I found that with my 6970, in trying to determine my maximum OC, the results were what you were seeing. I had to increase 1MHz, see what the hash was, record it, and increase another MHz, see what the hash was, etc. Increasing the OC by 1MHz could drop the hash by huge amounts. Add another 1MHz, and it could be back up where you would expect. I wish I had kept that spreadsheet to give exact numbers, but once I knew what I needed I erased it :) Title: Re: Raising the clock reduces hash rate? Post by: TripHammer on August 18, 2011, 02:32:05 AM thanks for the info, what are the numbers you are using now?
Title: Re: Raising the clock reduces hash rate? Post by: pixilated8 on August 18, 2011, 03:16:37 PM jb@miner0:~$ atitweak -s -A 0 ; atitweak -s -A 2
0. AMD Radeon HD 6900 Series (:0.0) engine clock 946MHz, memory clock 821MHz, core voltage 1.15VDC, performance level 2, utilization 99% fan speed 72% (4259 RPM) (user-defined) temperature 73 C 2. AMD Radeon HD 6900 Series (:0.2) engine clock 946MHz, memory clock 821MHz, core voltage 1.175VDC, performance level 2, utilization 99% fan speed 72% (4249 RPM) (user-defined) temperature 73 C I do not overclock the cards higher than what AMDOverdriveCtrl would be able to do. In fact, once I found my highest hash (~414) at 946MHz, I then proceeded to undervolt the card. Both cards use the same profile, but strangely enough the core voltage on #2 is different than #0. I'll have to look into that. |
