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Overclocking a Sapphire Radeon Toxic HD 5850 Toxic 2GB

Posted: Sat Jul 03, 2010 5:22 am
by firstlightimaging
I enjoyed Nathan Kirsch's May 25, 2010 review of the Sapphire Radeon Toxic 1GB HD 5850 - well written and informative; It helped me make the decision to purchase the 2GB version of this card. I've written Nathan directly but haven't received a reply (yet) - I bet he's a busy guy so instead I will post my questions here in the hope one of you might be able to answer some vexing questions I have about potential contradictions I have found in this legit article based on my own experience so that others might also benefit from the discussion.

First off, let me say that the Sapphire Radeon Toxic 2GB HD 5850 2GB edition is incredible! I plan to get a 2nd to crossfire in my big i920 rig running at 4.0GHz 24/7, 12GB of 1600 DDR3, multiple X25M 160GB G2 SSDs running in RAID 0 - this is my dream machine.

1) After installing the card I fired up ATI overdrive and and it appears to allow me to set values much higher than the screen cap in Nathan Kirsch's article. I installed CCC Version 2010.0527.1242.20909 and can set the sliders way higher for both the GPU and memory clock. Did they update that utility since then and is the article no longer accurate based on the original assertion that ATI OD can't be used to get beyond 775MHz for the GPU and 1125MHz for the VRAM, or, is it that although one can set the slider all the way up to 1000MHz that it will still only set the actual GPU clock to 775MHz or so? I see the screen capture Nathan included in his article shows that his dialog taps out at 775MHz and 1125MHz respectively, but mine shows it goes all the way up to 1000MHz (GPU range) and 1300MHz for the VRAM (compared to his dialog which shows it maxing out at 1125MHz). What gives? Could the Sapphire Toxic HD 5850 2GB edition simply behave differently than the 1GB edition of this card?

2) The article says we end users need TWO other utilities to OC these cards, the AMD GPU Clock tool AND MSI AfterBurner. Nathan asserted: "By using these two utilities you will be able to set the clock speeds (AMD GPU Clock Tool) and then you can manually set the fan speeds (MSI AfterBurner). If you try to manually set the fan speed in CCC and then use these programs to change the clock frequencies with the AMD GPU Clock Tool, you will find that when you launch a 3D application the fan defaults to auto speeds." However, when I run MSI AfterBurner, it appears to allow me to set all of the parameters, including clock frequency, memory frequency, voltage and fan speed. Has MSI Afterburner changed since this article? Why would we still need both AMD GPU Clock Tool as the article implies?

Note that the driver I am using is and Catalyst version 10.6 - could these be newer levels than what the reviewer tested just a month ago and explain why AfterBurner and ATI OD are no longer limited? We all know things do change quickly making information like this instantly obsolete, but that review is dated May 25th - so it makes me wonder.

Another issue: I am running Vista 64-bit Ultimate. When I tried to install AMD GPU Clock Tool it installed but would not run. I looked for a dedicated 64-bit Vista version but could not find one and it is not clear that the copies I have found support both 32-bit and 64-bit systems. When I clicked on its icon to launch it, it complained that I needed to run it as Administrator, but its context menu didn't allow me the option to run as Admin (even doing Shift+click only gave me "Run As" and it didn't say "Run As Administrator" - and when I chose it it still gave me error that I needed to run it as Administrator and it couldn't find the card. Sooooo, it looks like AMD Clock Tool doesn't run under Vista 64 and I am hoping the answers to questions 1 & 2 (especially #2) will tell me that Sapphire Radeon Toxic HD 5850 owners now need only MSI AfterBurner!

The final point I'd like someone to explain is when to increase the card voltage and in what increments. I understand to OC these cards it is best to OC the GPU first in 10MHz steps, then do the same with the memory, and when stable for each back off about 10MHz to ensure solid stability, but no one talks about how and when to adjust the voltage. I get the sense that the safe operating temp of this card is somewhere in the 70c or lower range, so in the absence of any other guidance I'd follow the same assumptions as I do with overclocking my i920 and assume I can up the GPU voltage to gain higher GPU and memory clocks until I hit ~70c if I want to leave it there 24/7 and adjust the fan speed accordingly? Is that a safe assumption?

I spent a few days scouring the best hacker sites and the web - no one seems to have these answers and I am hoping one of you might be able to shed some light on what I am finding now versus this recent article


Re: Overclocking a Sapphire Radeon Toxic HD 5850 Toxic 2GB

Posted: Sun Jul 04, 2010 7:45 pm
by Major_A
1) ATi could've raised the limits in the Overdrive panel. My little HD 5450 has the same limits as the last 3 or 4 drivers I've installed. I'm also running XP SP3 x86 so it might be a Vista/7 x64 change.
2) He probably said ATi GPU Clock Tool because MSI at the time didn't support the card. Like video games, and some applications, the new hardware needs to be in the config file for the program to work and the HD 5850 2GB might not have been in there yet. To my knowledge MSI released the latest version of Afterburner a few weeks ago and it should be good to go.
Link to MSI Afterburner v1.6.0 (6/10/10).
To unlock voltage, higher clocks, etc... you have to play with the config file. See how to do that here.
As for GPU Clock Tool I've never been able to get it to work on my HD 5450. Maybe my card isn't supported? From what I can tell though most people are using MSI's tool these days.
3) I'm not sure here. I don't know if MSI's tool limits this adjustment or not. But going from past overclocking experience I wouldn't push it past 0.5V until you test that thoroughly and see if it safe.

From what I know you can't judge stability solely on temperatures. You'll have to run a stability test is like MSI's Kombuster and look for artifacts. When the card artifacts it means one of three things.
A) The clocks are too high.
B) The card is running too hot.
C) The GPU/RAM isn't getting enough voltage.
Like any overclocking it's all trial and error.

Re: Overclocking a Sapphire Radeon Toxic HD 5850 Toxic 2GB

Posted: Tue Jul 06, 2010 8:07 pm
by Major_A
MSI's Afterburner and Kombuster v1.6.1 ...