SLI Noob

[Modeps]

Hello!

Roughly two years ago, I built a new PC featuring a GTX 560 Ti and a GIGABYTE GA-Z68A-D3H-B (SLI capable). My thoughts at the time were that once I wasn't happy with the video performance, I would just grab another GTX 560 Ti and SLI them. Cost was certainly a consideration with this setup at the time.

This week, I had a stroke of good fortune when a friend of mine handed me a pair of GTX Titan cards. After I picked my jaw from the floor and thanked him profusely, I ran home and installed one of the two cards, noting that I had enough space for both, but may not have the wattage. I'm currently rocking the Cooler Master GX - 650W. I fired up Skyrim, it defaulted to Ultra High, and I actually felt a little funny in my head as to how smooth it was.

First question: Do I need a more powerful PSU to use both? I know I need splitters for power at the very least as I don't have enough plugs to fit both cards.

Second question: Is enabling SLI basically just grabbing a bridge cable and saying go?

Thanks in advance.

 

[Deders]

If you keep Vsync enabled and use something like D3DOveride to enable Triple buffering then you might just get away with it, depending on what resolution you are playing at.

In fact If you are just using 1920x1080 or less than a single Titan will do perfectly.

If you don't like Vsync and Triple buffering then I expect you will find you PC will switch off when extreme graphical situations occur. In this case I would recommend at least 800W from a decent PSU manufacturer.

As for SLI connections, if you don't have a bridge, it will automatically bridge itself via the PCIe bus but this is not recommended if you have PCIe2. It might be passable but ideally there would be more bandwidth with PCIe3. I suggest getting the SLI bridge.

 

[Teizo]

Yeah, I'd get an 860ish watt PSU (Gold or Platinum Certified)...although you will be able to boot into windows just fine with your PSU (and like the poster above mentioned you may be able to get by with V-Sync since it will make the GPU run in a lower powered state). And as far as enabling SLI...just uninstall your gpu driver..shut down...install card...connect sli bridge...boot computer...

Then, when you get into windows after you re-install your driver, a pop up will appear saying 'this system is sli capable...click here to enable...'

That will carry you into the NV Control Panel. In the Configure SLI tab, just select 'Maximize 3D Performance'.

Done


And damn you are one lucky rascal...Once Gync comes out you won't need to upgrade your GPU's for a long, long time I think.

 

[bystander36]

If you keep Vsync enabled and use something like D3DOveride to enable Triple buffering then you might just get away with it, depending on what resolution you are playing at.

In fact If you are just using 1920x1080 or less than a single Titan will do perfectly.

If you don't like Vsync and Triple buffering then I expect you will find you PC will switch off when extreme graphical situations occur. In this case I would recommend at least 800W from a decent PSU manufacturer.

As for SLI connections, if you don't have a bridge, it will automatically bridge itself via the PCIe bus but this is not recommended if you have PCIe2. It might be passable but ideally there would be more bandwidth with PCIe3. I suggest getting the SLI bridge.

I see what you are recommending on the V-sync, trying to prevent the GPU's from drawing power, but if he is hitting his refresh rate, the last thing you want is triple buffing. Triple buffering is good when below your refresh rate, or with OpenGL, but causes latency with DirectX when hitting your refresh rate.

 

[Deders]

I see what you are recommending on the V-sync, trying to prevent the GPU's from drawing power, but if he is hitting his refresh rate, the last thing you want is triple buffing. Triple buffering is good when below your refresh rate, or with OpenGL, but causes latency with DirectX when hitting your refresh rate.

Vsync itself causes latency, Triple buffering is like a halfway house getting the best framerates the monitor can provide whilst below max refresh rates (that Vsync will limit to refresh rate of the monitor) whilst reducing the power the GPU might otherwise use to provide framerates above the monitor's capabilities.

I've experienced tearing without Vsync beyond my monitor's refresh rate and I'm not the only one to report this.

*Edit* If you play online games that demand responsiveness like a 1st person shooter with a twitch style gameplay than Vsync or Triple buffering aren't the answer, especially if other's aren't using it, It could put you at a disadvantage. but for most single player games Vsync and triple buffering will give the best image quality and low power consumption vs minimalistic responsiveness.

 

[Modeps]

If you keep Vsync enabled and use something like D3DOveride to enable Triple buffering then you might just get away with it, depending on what resolution you are playing at.

In fact If you are just using 1920x1080 or less than a single Titan will do perfectly.

If you don't like Vsync and Triple buffering then I expect you will find you PC will switch off when extreme graphical situations occur. In this case I would recommend at least 800W from a decent PSU manufacturer.

As for SLI connections, if you don't have a bridge, it will automatically bridge itself via the PCIe bus but this is not recommended if you have PCIe2. It might be passable but ideally there would be more bandwidth with PCIe3. I suggest getting the SLI bridge.

I've never had any issues with vSync personally, though I know generally it's frowned upon (still not entirely sure why). Will any old bridge do? Looks like they're pretty cheap on Newegg.

 

[Modeps]

Yeah, I'd get an 860ish watt PSU (Gold or Platinum Certified)...although you will be able to boot into windows just fine with your PSU (and like the poster above mentioned you may be able to get by with V-Sync since it will make the GPU run in a lower powered state). And as far as enabling SLI...just uninstall your gpu driver..shut down...install card...connect sli bridge...boot computer...

Then, when you get into windows after you re-install your driver, a pop up will appear saying 'this system is sli capable...click here to enable...'

That will carry you into the NV Control Panel. In the Configure SLI tab, just select 'Maximize 3D Performance'.

Done


And damn you are one lucky rascal...Once Gync comes out you won't need to upgrade your GPU's for a long, long time I think.

Seems pretty easy. What's Gync?

 

[bystander36]

Vsync itself causes latency, Triple buffering is like a halfway house getting the best framerates the monitor can provide whilst below max refresh rates (that Vsync will limit to refresh rate of the monitor) whilst reducing the power the GPU might otherwise use to provide framerates above the monitor's capabilities.

Yes, triple buffering is for when you are below max refresh rates. It unfortunately has a side effect in DirectX games, when you hit your refresh rate. It starts sending images a frame behind the most recently created frame. This makes you a full frame behind, or 17ms additional latency on a 60hz monitor.

With two Titan's, he's likely going to be at that refresh rate cap the whole time. Turning off triple buffering is the best thing in this case.

 

[Teizo]

I've never had any issues with vSync personally, though I know generally it's frowned upon (still not entirely sure why). Will any old bridge do? Looks like they're pretty cheap on Newegg.

To be on the safe side, get a flexible SLI Bridge at first. They are super cheap on Ebay. Then once you get an understanding of the proper length between the two cards...you can get one of the more fancy rigid connectors perhaps. Just make sure at first the connector you chose is flexible. I say this because the last thing you want is to order a rigid one and have it not fit correctly.

 

[Deders]

So long as the SLI bridge works, I have had issues with the flexible SLI bridge that came with my MSI motherboard, but as soon as I plugged in the solid EVGA bridge from my previous MB everything was fine again.

 

[bystander36]

Neither should perform better than the other and if one doesn't work, it is due to a defective part, not because it's ridged or flexible.

If I were to have a single SLI bridge to choose, I would choose a 100mm flexible bridge, as it'll work for almost any setup.