I have a simple question, i have a Zotac 780 OC 3gb 384 bit

i want to go SLI do i need to buy the same exact card from Zotac (Who are really hard to find) or i can go with an Asus card that support SLI ou a MSI

Just need a 780 3gb company doesn't matter

As long as it is the same gpu (GTX 780), has the same amount of VRAM (3GB) and the same bus width (384-bit). And they have to running in at least PCI-e 8x.

You mix vendors and clock speeds np.

You can run the 6gb version too, But it will just cap them both @ 3gb.

Also, whats with the 8x min?

Maybe he's referring to the performance bottleneck of higher end cards? I don't necessarily understand his post either.

No you can't. That's for AMD Crossfire.

And SLI certification requires the GPU to run at least 8x, the GPU will not work when it's ran in a 4x slot in 3-way or 4-way SLI. Once again, Crossfire works with 1x. You obviously can't have SLI certification on a mobo which does not support 8x + 8x or 16x + 8x so two-way is not a problem unless you have RAID cards etc.

e: Those are the specifications provided by NVidia and other sources explaining them in detail.

This post was edited by nexcoor on May 14 2015 04:12am

yes you can

and you can force sli on non sli mobos with "other" drivers as long as there another slot

and different clock speeds might need manual adjustment

This post was edited by yupitsmeh on May 14 2015 11:00am

You have to re-educate NVidia's staff.
https://forums.geforce.com/default/topic/469402/

Clockspeeds can differ, np. Running SLI'd GPU's in a lower than an 8x lane will result in a failure, haven't read about it working in 4x or lower environment. Other than that the certification can be ignored (like you said).

Different clock speeds can cause freezing hence why i said might and/or upping the volts
Sli has always had an known issue with one card running undervolt and/or underclock

Every driver update i must fix my clocks n volts on 2nd card Never hits what it should

Been like this since as far as i can remember 8k. Some cards aren't affected by slightly lower clock And or volt

This post was edited by yupitsmeh on May 14 2015 11:20am

The 8350, for example, has 16 PCI lanes. So if you run one card in a slot that is 16x it will run at 16x.

When you use 2 GPU's it reduces the amount of lanes per GPU depending on your chip. In this case, 8 each GPU, regardless if its in a 16x slot or not.

If you had a 5xxx series for example, those chips allocate 40 lanes so you could run 16x 16x no prob.

The difference between 16x and 8x isn't even noticeable so 8x 8x is okay but bottlenecking does begin at 4x.

So if you run tri fire (or SLI) on a chip that only has 16 lanes it will be 4x 4x 8x, which isn't ideal.