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SLI in Windows with 1 MVC card

s.m.t.

s.m.t.

macrumors 6502
Original poster
Mar 7, 2010
285
22
I had one of my 980tis flash by MVC (love having a boot screen, thanks MVC!) but at the samd time I got a second 980ti that I wanted to SLI in Windows. I don't get the option in the Nvidia control panel to enable SLI. Just unistalled and reinstalled the nvidia drivers, but still no option.

Running a Mac Pro 4,1 (flashed as 5,1) and Windows 10 64bit.

Anyone else running SLI in Windows with one flashed card and one stock?
 
I'd ask MVC, but:

How are you powering the two cards? Two 980ti cards is a lot in a Mac Pro.

Are you certain the second card is working?
 
ActionableMango said:
I'd ask MVC, but:

How are you powering the two cards? Two 980ti cards is a lot in a Mac Pro.

Are you certain the second card is working?
Click to expand...
I soldered two 8pin cables straight to the power supply, 6pin coming from the logic board. Both cards show up in Mac and Windows.
 
I vaguely remember something about SLI requiring either an SLI certified motherboard (which the Mac Pro isn't), or hacked Nvidia drivers in order to get past the software authentication. This is old information though, and I don't know if it is still relevant or still possible:

http://www.insanelymac.com/forum/topic/80668-new-mac-pro-with-sli/
https://forums.macrumors.com/threads/2x-sli-gtx-590-in-mac-pro.1238942/#post-13467167
https://www.techpowerup.com/forums/threads/how-to-enable-sli-on-pre-i7-i5-hardware.60844/
https://forums.macrumors.com/threads/sli-for-mac-pro-under-windows.974439/

The last I heard is that the SLI hack worked in the past, but isn't maintained so therefore this is no longer possible.

Perhaps you are more up to date than I am, in which case I apologize for the old info. I'm just trying to share what I remember from back in the day.
 
No worries, appreciate any input... Maybe that is the case, could also be due to the one flashed card, and I am also wondering if I have a bridge issue. I bought one of the EVGA V2 bridges that is supposed to light up, but never does... Not sure if it does till you enable SLI though...
[doublepost=1469490273][/doublepost]MVC just replied to my email and stated this...

The issue you actually have is that the Mac logicboard isn’t “certified”

There used to be a product called “Hyper-SLI” which isn’t used anymore.

Then :”Different SLI” came along

I haven’tmessed with them in a couple years, but they are needed to make SLI work.
 
So no luck yet, ran through the setup and pre-reqs to setting up DifferentSLIAuto 1.4 with 364.51 drivers. Got everything to install and disabled driver signing and enabled test mode... But still missing the option to enable SLI...

Will have to play with it some more...

If anyone else out there as played with this and got it working, would love to hear your thoughts...

Going to post here as well to try and get some direction...
https://www.techpowerup.com/forums/threads/sli-with-different-cards.158907/page-77
 
I used hyper SLI on my Mac Pro when I had dual 680s installed. Both were self flashed and things mostly just worked aside from the usual SLI quirks. Haven't visited that set up for a while though. Good luck OP!
 
thornslack said:
I used hyper SLI on my Mac Pro when I had dual 680s installed. Both were self flashed and things mostly just worked aside from the usual SLI quirks. Haven't visited that set up for a while though. Good luck OP!
Click to expand...
That's encouraging as it must be a software limitation then. What model Mac Pro?
 
It was a 4,1 to 5,1. I was running Windows 7 ultimate at the time. I forget why Hyper SLI stopped being supported but it continued to work on my system up until I moved to a single card solution. I used an Asus SLI connector I bought for 2$ off amazon or something.

While it was a cool experiment and did offer some performance gains for gaming, I wasn't pleased with the noise, heat, and power I was going through. Also because of the cMPs older IPC the scaling benefits of SLI take a bit of a hit. I'm pretty sure with even higher end cards like big maxwell you'd be severely CPU limited.

Unrelated, but if you're short on Pcie slots, I used a x4 riser card in slot 3 and took out my last hard drive in favor of mounting a sata6 pcie card there while maintaining both GPUS in x16 slots and retaining slot 4 open.
 
Okay so same as I have so it certainly can't be a limiting factor due to hardware , thanks!

Yeah temps may still be an issue. Assuming I get it working, that will be the next thing to watch.

Thanks again for the info, much appreciated!
 
s.m.t. said:
I bought one of the EVGA V2 bridges that is supposed to light up, but never does... Not sure if it does till you enable SLI though...
Click to expand...

I saw this on an Amazon review of that EVGA bridge:

The EVGA logo lights up when the cards are set to SLI mode within the NVIDIA control panel. When the cards are not in SLI, the logo dims to let you know you are no longer in SLI. This provided me with a great opportunity to trouble shoot video card SLI problems when one of the cards was not properly connecting to SLI (it was the card's fault).
 
Hmm... thinking I should try my cards and bridge in a PC...
 
So did a clean install of Windows 10 to another hard drive, and still no luck. I am going to get another bridge and try that next. If it has been done before on a Mac Pro, it must be something I am doing or with my cards and or bridge. Thought about trying a Windows 7 install as well.
 
Does anyone know if it is possible to modify the EFI on the Mac Pro to make it appear as SLI Certified?
 
s.m.t. said:
So no luck yet, ran through the setup and pre-reqs to setting up DifferentSLIAuto 1.4 with 364.51 drivers. Got everything to install and disabled driver signing and enabled test mode... But still missing the option to enable SLI...

Will have to play with it some more...

If anyone else out there as played with this and got it working, would love to hear your thoughts...

Going to post here as well to try and get some direction...
https://www.techpowerup.com/forums/threads/sli-with-different-cards.158907/page-77
Click to expand...

Looks like "Nate" just got it working on a Mac Pro yesterday (see page 78 of that linked thread). It wasn't working with DifferentSLI 1.4, but did work when trying DifferentSLI 1.5.

Have you tried 1.5?
 
Sadly, yes... Tried with 1.5 and 368.81 Saw he/she had 660s... I haven't found anyone who had successfully done it with 980tis... Though I am not sure why they would be different...

I am completely at a loss and just chalked up the idea... Will just live with the one card till 1080tis are MVC flash-able... :)
 
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