The Lock Reference Divider ?

[Lt_Omega]

Hi there,

I'm still new to ATi Tool

Great tool that by the way.

Any how i just want to ask if anyone out there could briefly explain what the lock reference divider does apart from the obvious (Fix speed increments). Does it keep the memory and core speeds in sync or somewhere along those lines?

Just today i was doing a test on finding out the best balance between memory and core speeds ( I was using aquamark3 and 3DMark 03).

One thing i noticed was that i couldn't always fix a range of core speeds on to one memory speed [tearing/vectoring (if its the right word) in the window doesn't seem to influence ATiTool's results]. It kept fluctuating till i clicked on the lock reference divider.

Another thing i noticed and this could just be me guessing, the best reference divider ratio is the ratio that was set at the default clock speeds. For me the default reference divider was 18 (1.50 MHz increments).

So yeah, apart from wondering what the lock refernce divider does, i'd also like to point out that the best refernce divider ratio is the one that is found at the default speeds (by the way always unlock the reference divider before hitting the default ratio, the divider ratio at the default speeds may be influenced by a previous ratios)

 

[zealot`grr]

well, back then when R300 was introduced there was some discussion about the gpu / mem ratio - can't remember the results

nowadays overclockers think higher > better I guess... would you like to share some scores you benched /w different ratios?

 

[Lt_Omega]

Aiye, I was just about to post scores using those reference divider values.
Those reference divider values seem to be dependent on core speeds rather than memory speed (I was doing my initial tests while focussing on memory speeds, thats why I felt the fluctuations were too wild) . Some of the information i posted about the best reference divider value is rather redundant to what i noticed now.

At 18 the max core speed supported for me is 382.5. If i go any higher the lock reference divider turns into one of 17 value (or a value less than 17 if not done right but never more than 17, may post procedure in a later post.)

At 17 the core speed goes upto 405 MHz. One more increment and the reference divider value can only do under 16.

And 16 goes upto 430.31 MHz. Any higher, you guessed it, the value reduces to 15 automatically

On 15 the core goes well past my core limits so i can't help out with information on what core speed does the lock reference divider value turns 14 (it was still 15 when i pushed the core to 444MHz, couldn't go any furthur because at around 443 my core dies out in under a minute!)

Anyway a quick list of my stable core/ memory ratios
Default:324/189 (2,041 score in AquaMark03 running with softmod catalyst 4.12 Beta, 4.10 produces very low scores in Aquamark03, 1,600 approx.)
Aqua Mark 3 GFX scores

18: 382.50/184.50 2,307
17: 405.00/183.44 2,364
16: 430.31/183.09 2,445


As can be seen, my memory has to be downclocked for me to OC the core. Well i'm on a Sapphire 9600NP 256 MB running on elixir memory. I'm still testing the 17 and 16 reference divider memory values for system stability (any higher values will cause tears/distortions on the rotating cube but no errors are detected when scanning for artifacts, I only plan to do cautious OC'ing so I don't plan to push the core past 430.31 MHz which is the maximum i can do with a 16 reference divider.).


Well enough of my rambling,
Any one care to add information on the lock reference divider ( I saw the definition on a sticky but i cannot recall much about it!)

 

[zealot`grr]

interessting... I have to think about this

 

[Stephen M. Smith]

Also, quite a few of us have discovered that with recent Catalyst releases, the screen will be garbled when resuming from standby or hibernation and the divider is lower than 4.5. No idea why...

One the things I appreciate about ATI Tool is that the divider doesn't matter to you -- you set the gpu and memory to what you want and ATI Tool figures out the most appropriate divider to get you want you want. However, I have to use that lock divider check box as of Catalyst 4.8 (or maybe 4.7) to prevent a garbled display on standby resume.

Steve

 

[Lt_Omega]

Mmm well before i start any divider setting/locking.

I first unlock the divider, load up a couple of profiles and finally load up the default clocks.

And then only do I lock the divider ( So I'm sure the lock is the proper default values.) I've had divider values of 6 when i know the minimum possible divider value on my machine is 15 or 14 at most.

Try doing this Stephen, once you got the proper default divider value, lock the divider, load up the profile you wish to use (Hopefully the clock would set, sometimes the speeds may be a few MHz slower if your at the maximum core speed of that divider value, but these most likely are for safety reasons) and check what divider value is set automatically. This may lead to more OC stability by lowering the chance that the divider value is off balance.

One example of the clocks being downclocked, is when at value 16, my max core is 430.31, but when i load the profile both the core and memory speeds go down a notch. ATitool seems to want me to sacrifice one of the speeds, so what i do is adjust to the lower core speed while keeping the higher memory speed.
With numbers:
Theoretical 16 divider max. speeds: 430.31/183.09
Values when profile loaded: 428.31/182.25
Adjusted profile : 428.31/183.09 (lower core, higher mem)
Values when adjusted profile loads: 428.31/183.09

 

[Stephen M. Smith]

What card do you have? The default divider for my 9800XT is 6.75, but it goes as high as 13.75. Are we talking about the same thing?