"Synchronizing" 5970 and 5870?

[Jan Kyster]

Have been running this Tri-Fire combo some time now for stability and temp-tests. All fine. Good scaling too!

However, first time system is switching to 3D-mode, there are some artifacts.
By alt-tabbing to desktop and back to game, all's clear again. Next time there are no issues when entering 3D-mode.

Have found a few links where this issue has been solved by clocking all GPUs to same speeds, but when I look in the BIOS settings, I need some guidance.

The 5870 BIOS:

The 5970 BIOS:

I've tried using CCC to give the 5970 same speeds as 5870, 850/1200MHz.
Ran a CCC test with "OK!", but when loading game, gpu froze and got artifacts.
Guess this is because voltage wasn't trimmed as well?

Initial thought was to push 5970 to same speeds as 5870, but not sure if it's "worth" it? Perhaps a compromise, setting all three gpu to like Core 800 MHZ and Mem 1000 MHz.

Voltage settings? Set all to same as the 5870?
Also for GPU Registers and VTT registers?

And what about the "Clock info 05" setting, that the 5870 has, but the 5970 don't? Use same setting as Clock info 04?


Any help/guidance will be appreciated!

 

[kn00tcn]

well, you better make sure your 5970 on both gpus can handle the extra voltage, heat, speed

i wouldnt bother after how old these cards are, stay with 5970 & sell the 5870, then get the coming soon next gen single gpu (or sell the 5970 & get the next gen)

 

[Law-II]

Hi

Have you tried selecting your HD 5870 in ccc and changing the core to 725MHz and Mem to 1000MHz to see if the issue is related to the vga bios settings? do you still get artifact's when entering 3d with this setting. - if Yes - you may have driver issues rather than vga bios issues. -If NO- the Artifacts have dissapeared; go to next stage

NEXT
How to get to 800 core and 1100 mem don't be in a rush

-In Catalyst Control Center; navigate to the Performance /AMD Overdrive - under the heading Select GPU to configure you should see your primary card ATI Radeon HD 5900 Series attached to your Philips Brilliance 240S1SB then a second entry ATI Radeon HD 5900 Series and a third ATI Radeon HD 5870 make sure that the clock and mem speeds are the same on each tab before testing. Use FurMark_v1.7.0 in full screen mode at your native resolution to enable crossfireX, use the space bar to toggle if your screen becomes unstable at high clock speeds, be prepared to reset you system if it becomes unstable (FurMark_v1.7.0 will flush any instabilities out in the open)

(test your new base clock first to ensure you are starting out with a stable system)
From your base clock of 725MHz core and 1000MHz mem raise the core and mem by 5MHz at a time and test for stability; your current goal of 800MHz Core and 1100MHz mem

with experience a Sapphire HD 5970 should be able to hit 800Mhz core and 1100MHz Mem on air cooling with no voltage increase. (the HD 5970 VPU's were binned and put to one side at production and operate at lower voltage)

nb: some people only oc; however down clocking can work wonders on occasions (you may drop a frame or two however we are talking about a card that can produce 200fps in FurMark and with a HD 5870 in crossfireX may be more fps) let the TPU members know your findings

Hope this helps

atb (all the best)

Law-II