How many graphics cards

[tricky]

(I don't think I can post in the RT forum (we are not an RT owner...yet!) so bare with me)

Its been a while since I've looked at building a workstation, but I am hoping, at some point soon, to start building a test-rig for Vray RT GPU. I have a few, somewhat basic, questions:-

1) How many Graphics cards can you put into a Windows 7 x64-based machine? I always thought 2 was the limit.

2) I've never built a machine with more than 1 card. With a multi card setup, which one do I actually connect my monitors (2 of them) to?

3) Our plan is to have workstations with fast GPU rendering qualities, and leave our render farm as CPU-based rendering for final renders. RT is essentially for 'test rendering', whereas final renders (vrimg files), to get all the render elements and alpha channels, need to be rendered 'traditionally'. Am I right in my thinking?

4) Our workstations, though powerful when we bought them, are becoming a bit tired. They have quad-core intel CPUs, 8GB Ram and ATI v7350 graphics cards. I now realise ATI cards aren't supported by RT GPU. Would a 'quick fix' to bring them up to speed be to replace the graphics cards with the best gaming cards we can get? The main boards are D975XBX2 and this is what the spec says:-
"Three PCI-Express x16 slots for CrossFire (top two running either x16 and x1, or x8 and x8, and third slot locked to x4".
What, therefore, would be the best setup for GPU based rendering? Does this suggest I can put 3 cards in there?
<EDIT: A quick 'google' suggests I cannot run multiple Nvidia based cards in this motherboard. Typical. So this would mean I either rip out the motherboard as well, or cross my fingers that RT GPU will be supported with ATI soon>

[vlado]

1) How many Graphics cards can you put into a Windows 7 x64-based machine? I always thought 2 was the limit.

It depends on your motherboard (for example mine can fit only one card); Windows 7 itself supports up to 8 video outputs; some cards have two or three outputs (e.g. 2 DVI and 1 HDMI), so they all count (there are hacks around this, they are messy).

2) I've never built a machine with more than 1 card. With a multi card setup, which one do I actually connect my monitors (2 of them) to?

Each card must have something attached to it in order to be recognized by Windows (either a monitor or a dummy plug); the Tesla cards are the only ones that can work without anything attached to them. Since you have two monitors anyway, you can just as well attach one monitor to each of the two cards.

3) Our plan is to have workstations with fast GPU rendering qualities, and leave our render farm as CPU-based rendering for final renders. RT is essentially for 'test rendering', whereas final renders (vrimg files), to get all the render elements and alpha channels, need to be rendered 'traditionally'. Am I right in my thinking?

Yes, this is correct.

4) Our workstations, though powerful when we bought them, are becoming a bit tired. They have quad-core intel CPUs, 8GB Ram and ATI v7350 graphics cards. I now realise ATI cards aren't supported by RT GPU. Would a 'quick fix' to bring them up to speed be to replace the graphics cards with the best gaming cards we can get? The main boards are D975XBX2 and this is what the spec says:-
"Three PCI-Express x16 slots for CrossFire (top two running either x16 and x1, or x8 and x8, and third slot locked to x4".
What, therefore, would be the best setup for GPU based rendering? Does this suggest I can put 3 cards in there?
<EDIT: A quick 'google' suggests I cannot run multiple Nvidia based cards in this motherboard. Typical. So this would mean I either rip out the motherboard as well, or cross my fingers that RT GPU will be supported with ATI soon>

It would probably be best not to rush things; you can try upgrading one or two machines and see how that works.

Best regards,
Vlado

[tricky]

Thanks Vlado.

I'd like to get onto the beta programme, but we aren't RT users, and at the moment, we're not able to buy into RT1.5. We'll just see how things pan out...

I wonder how RT GPU would run on my laptop? It'd be an interesting experiment. It only has 2 cores on the processor, and the card is a GeForce 8400M GS. Would RT GPU even work?

[vlado]

We might be able to get you a time-limited evaluation license if you email us to vray@chaosgroup.com

Best regards,
Vlado

[tricky]

Thanks Vlado.

[flino2004]

if you plan to have 2 gamers video cards maybe make sense you have one tesla with 3GB-4GB ram....Ram would be a issue for architectural visualization i think, specially if you use xrefs proxies and big maps

[tricky]

Mmm. Anyone using Tesla cards then? How does performance compare to say, a 460 Geforce card, on Vray RT GPU?

[flino2004]

the performance is very similar than 480s but the main feature is the memory... The only vray user that i know has a tesla is Frances, she uses it for Arion (fryrender)

Fernando

[kein_plan]

hi, i think for now the most interesting card ist the 460 with 2gb of ram. it is only half of the price of the 480 and has more ram. the 460 uses only 160 watt max, the 480 is 298 watt max. i will just order two of them and build a workstation with them. so next week i can tell you more...