Dual Monitor setup using two video cards

[Cookie Monster]

I was just wondering about if you could you have a setup where say you had a GTX480 and GT240 with the main monitor hooked up with the GTX480 and the second monitor with the GT240. The aim is would be to have the main card throttle down to its low power consuming 2d clocks as we know that cards throttle down to some semi 3d clocks.

Is this possible? and what could be the downsides of this? (i could think of driver issues when moving stuff between monitors or having the same source displayed by two monitors)

 

[Lonyo]

Yes it's possible.
No real issues, although having a video across both might not work (although that can be troublesome even with 2 monitors on one card with the wrong overlay mode set).
For everything else, shouldn't be any issues (based on experience with NV 2+1 over 2 cards in XP and ATI 2+1 over 2 cards in Win 7)

 

[Cookie Monster]

Yeah, having video on both monitors might not really work (even on a single video card setup where one has GPU acceleration on for blu ray movies - unless they fixed that).

Interesting, since my GTX260 doesn't clock down to its 2d clocks. Might be interesting to twinker around with this idea.

 

[WelshBloke]

Couldn't you just set up RivaTuner to force 2D/3D clocks?

 

[Cookie Monster]

I could but there is a reason why the single cards dont drop down to their idle clocks when using multiple monitors. I forgot what the exact details were though, but its probably got to do with instability.

 

[WelshBloke]

Why not try it and see, cant do any harm.

My card (an old G80 based NV card) has no issues with 2 monitors and forcing low clocks.

 

[fleshconsumed]

Couldn't you just set up RivaTuner to force 2D/3D clocks?

He could, I've done it. Problem is you can only force GPU/memory clocks with RivaTuner, but you can't lower down voltage on GPU chip, so the power usage/heat remains closer to 3D mode level as opposed to 2D mode.

As far as your G80 working correctly, well, I guess you're lucky. It's a well documented bug (that nVidia refuses to fix) in nVidia drivers that GTX200 series does not downlock itself to 2D mode with two monitors attached.

 

[LokutusofBorg]

As far as your G80 working correctly, well, I guess you're lucky. It's a well documented bug (that nVidia refuses to fix) in nVidia drivers that GTX200 series does not downlock itself to 2D mode with two monitors attached.

Does this apply to the GTS240? Or is that still the constantly-rehashed 9800 line that just won't die, and so doesn't have this bug?

 

[Cookie Monster]

I think it applies to all cards. Its a hardware limitation from what I remember. The G92 cards will use their full 3d Clocks when using dual monitors.

Since a GT240 isnt very power hungry (~6W idle on windows according to xbitlabs) and dirt cheap, I might try this out instead. Could potentially be a PhysX card too if I the games I play have it.

 

[fleshconsumed]

Does this apply to the GTS240? Or is that still the constantly-rehashed 9800 line that just won't die, and so doesn't have this bug?

I don't know. I know my GTX260c216 has this bug. When I had 8800GT I never noticed 2D/3D clocks because the card never put out any significant heat even in 3D mode. It's only when I switched to GTX260 that I noticed my room was way hotter than it should have been and then traced it to the videocard always working in 3D mode pumping too much heat in the room.

 

[WelshBloke]

He could, I've done it. Problem is you can only force GPU/memory clocks with RivaTuner, but you can't lower down voltage on GPU chip, so the power usage/heat remains closer to 3D mode level as opposed to 2D mode.

As far as your G80 working correctly, well, I guess you're lucky. It's a well documented bug (that nVidia refuses to fix) in nVidia drivers that GTX200 series does not downlock itself to 2D mode with two monitors attached.

You cant on a G80 but you can alter voltages automatically with the newer GPU's.

You could set up two profiles in afterburner one with low clocks and voltages and have it load at start-up the other with your maximum overclock and set it to auto start on the launch of a 3D app.

 

[fleshconsumed]

Didn't know that. I only use RivaTuner and it doesn't allow you to control voltage. Thanks for letting me know.

 

[Cookie Monster]

Finally got the time to install my hardware that was gathering dust for weeks now. But before installing I did a few things. Firstly, I did change the stock thermal paste with MX-2, and undervolted the stock voltage of the GTX470 from 0.987V to to 0.95V (its at 0.88 during 2D). Ive also designed a fan profile for the GTX470 using MSI afterburner. The stock fan isnt loud til it hits 65% and up for me. The stock fan sits at 40% fan speed til you hit very high temps where it will start to spin up.

Anyway the first monitor is hooked up with the GTX470 and the other one is hooked up with the GT240.

Idle temps on the GTX470 is 40C (ambient is around 23~24C). The clocks drop down to its 2d clocks. Idle temps on the GT240 is 30C. Its also inaudible because the fanspeed is at 40~45%.

If i boot up furmark using 1680x1050 with 4xAA, im getting 85C max at 70% fan speed.