Second GTX260 doesn't use 'performance 3D' clock in-game?

[acer0169]

I really hope someone can help me with this because it's had me scratching my head for hours.

I have two GTX 260 core 216s in my computer in Hybrid SLI and I use RivaTuner to overclock and increase the fan on them.

When I'm not playing games, they both clock at either 300MHz or 400MHz. If I check rivatuner, the 300MHz clock is for "standard 2D" and the 400MHz is for "low-power 3D". When I play a game (GTA for example) they are ment to clock up to the "Performace 3D" clock of 576MHz but I've overclocked them to 615MHz. When I play games, I normally run Everest Ultimate to check on temps etc, but I've noticed that only the prim. card clocks up to this full clock, the second card stays at 300MHz? Surely I want them both fully clocked whem I'm playing games as 300MHz is less than half the clock speed I want out of the card.

Does anyone know how I can force both cards to run at full speed?

Also, does Hybrid SLI cause this? I'm going to restart and try without using Hybrid SLI and post back here, just wondered if anyone knows about this and how to solve?

Thanks,
ace.

 

[rockyjohn]

Have you tried running prime95 to see what happens with max load?

 

[acer0169]

In Prime95 the first GPU clocks up to my desired clock, the second stays at Standard 2D of 300MHz. I've now tried without Hybrid SLI and it still does this?

 

[rockyjohn]

What mobo do you have? Are both PCIe x16 slots a full x16? Although I admit I would expect more than 300 MHz out of the second one even if only x8 bandwidth.

Have you tried switching the slots the boards are in to see what effect that has? Is it the board or slot that determines the faster one?

 

[acer0169]

I have a XFX 750a. I know it's a *** board but I used to have two 8600GTS's in there in SLI and they never had this problem.

I've tried just one GTX260 in the bottom slot (which is prim when there is only one card) and it ran at rull speed. When SLI is enabled the top slot is the prim slot, which is only x8x8 when in SLI, but it's the top slot which is using the higher (correct) clock speed.

It just seems very odd.

Both slots work fine, they both can support the top clock, and with my old SLI setup both cards ran at full clock, now I've upgraded to the 260's, it seems to keep the second card always on the 2D clock speed.

I don't think it's hardware that's limiting it, I think it's software personally.

 

[acer0169]

No one has any ideas about this?