SLI - Worth it, or gimmick?

[Fear]

Anyone here running SLI?

I'm considering getting myself a second one of these whilst they are still for sale, mostly because I can. I'm after increases FPS at 1920x1200, more than anything.

I'm slightly curious as to if they are worth it, or if they are just a load of gimmicky old rubbish that is more trouble that it's worth.

[Dog Pants]

I've never bothered with SLI, despite me buying MOBOs to accomodate it for the last two upgrade, because I've been led to believe that the performance increase from buying a second card isn't as good value for money as just buying a new card. The boost isn't all that much. Also, bear in mind that you'd need a hefty PSU.

I'm no expert though, one of the techies could probably give you a more informed opinion.

[Fear]

Thanks for the reply.

I have the PSU for it, and the motherboard. I kinda designed my system so I could put one in, but couldn't justify a second at that time. My only concern would be cooling - my case has a side fan designed for pointing at the gfx card(s) - but it's a noisy fucker so I'd prolly have to do the old 5v trick.

[Dr. kitteny berk]

Swings and roundabouts really.

You will see a decent performance boost (I think 30-70% is the going rate depending on the game) but it does have downsides.

I think SLI still doesn't support multi-monitors (chicken will be able to tell you) it's meant to soon though IIRC.


If I was on a G92 8800GT(s) around this time, I'd certainly buy a second one, the performance boost should be noticeable, and it's unlikely they'll get much cheaper, looks like they're clearing stock for the 9x00s.


edit: just read your first post properly, you should see a decent boost at 1920x1200 with sli.

[Fear]

Hmmm, I'll think I do it then... I'll get a fan controller thingy too so I can turn up the jungle-juice as and when.

[HereComesPete]

Multi-monitor is a bit picky. But the last few firmwares has seen a lot more people getting support from on desktop without the need for a reboot. It's not definite though.

A new fan (I take it it's 120mm flavour?) along the lines of a noctua or a scythe s-flex will see good airflow and hardly any noise. If you don't want to spend on one of them something like an arctic cooling with pwm* will still offer good bang for buck.


*pulse width modulation, it turns the fan on and off at incredible speeds dependant upon voltage and load, with a far higher efficiency than a potentiometer, the switching noises are absorbed through inductors/capacitors so it doesn't generate extra noise. Works very well with fan controllers too.

[TezzRexx]

Regarding Berk's post, what are the major down sides to an SLi set up?

[HereComesPete]

You do of course have to have extra beefy components in terms of a proper sli mobo and a bigger better psu with plenty rails is needed too.

Extra heat. Picky drivers. Lack of support for older games. More monies spent running the thing. No noticeable improvement in some games. Multi-monitor support isn't as perfect as they make out. The outlay on a second card that may end up being replaced by a newer single card solution sooner than you think.

editz gop gop gop gop gop gop gop gop gop gop...

[Dr. kitteny berk]

Regarding Berk's post, what are the major down sides to an SLi set up?

Heat, power consumption (and PSU needs enough connectors to feed them), lack of multimonitorness.

Plus sides of course are better performance, make machine last longer before major upgrades.

[TezzRexx]

Hmm, the most off putting for me is the power consumption. I bet that could raise bills very quickly indeed.

[Dr. kitteny berk]

It's probably not really as bad as you think. an 8800GT will eat 105W IIRC, should be much, much less at idle.

Turn a light or 2 off while you game and you'll more than make up for it

[HereComesPete]

Also, if you fold on two cards and a cpu then you'll have no need for the heating. This will save money, even if it leaves the rest of the house freezing.

[Dr. kitteny berk]

Also, if you fold on two cards and a cpu then you'll have no need for the heating. This will save money, even if it leaves the rest of the house freezing.

ISTR CUDA/gpu folding only supports one gpu at a time, not sure though.

[deject]

ISTR CUDA/gpu folding only supports one gpu at a time, not sure though.

http://folding.stanford.edu/English/FAQ-NVIDIA#ntoc17

What about multi-gpu support?

Yes, you can add the "-gpu N" flag (N starts at 0) to your extra parameters in the advanced page of the systray clients, or the advances settings of the console clients. Again N starts with 0 not 1, so your primary display is 0, the next is 1, etc. Each client if you are running more then one needs a different -gpu and a different machineD, and a different working directory, so follow the instructions for multiple clients.

For Tesla and other non-desktop cards, we have the "-forcegpu" flag, which will make the client ignore what it thinks the GPU is, but the core will not work if that card is unsupported, so use with caution. To use this flag you need to supply it with a gpu core type to use as an override. Currently these are ati_r600, ati_r700 and nvidia_g80. This flag may also help for headless multi-gpu setups on which the client refuses to acknowledge the presence of your GPUs. The -forcegpu flag can be use in conjunction with the -gpu flag to horse the client to try and use the given gpuid. For example:

Folding@home.exe -gpu 2 -forcegpu nvidia_g80

Would horse the client to try and run the NVIDIA core on the 3rd (2 + 1) cuda enabled device in the system. Similarly:

Folding@home.exe -gpu 3 -forcegpu ati_r600

Would horse the client to try and run the ATI core on the 4th (3 + 1) CAL enabled device in the system.

For a more detailed set of instructions, please see these links

1. FAQ on the forum
2. Windows GPU Guide

We will update our main FAQ in time with these details, but we are also working on ways to handle this from an installer directly.

[Dr. kitteny berk]

Ahh, must have added that since I last looked.

[Dr. kitteny berk]

this might be of interest.

http://www.vr-zone.com/articles/Nvidia_ ... /6110.html