SLI PCI Lanes

[paps511]

Not sure if this belongs under CPU or GPU, but I was wondering how many PCI lanes I would need to SLI 2 1080Tis? Is it possible to run them both at 16x? or would it even matter?

I plan on upgrading from my 4690k to either a 6800, 6850 or 6900.

 

I don't stream but I do a bit of development work

[DaftBehemoth]

As long as you have a motherboard that supports 8x PCIE to both cards, you'll be totally fine. 

[tarfeef101]

You only need 16 (8 each)

 

You can run them both at 16x (which isn't necessary) if you have a motherboard (of course with SLI support) that has 2 slots wired for 16x, and a CPU with at least 40 lanes off of it.

[The Sloth]

8x will be enough, you need 16 lanes for development i suggest a 6900 or ryzen. 

[typographie]

10 minutes ago, paps511 said:

Is it possible to run them both at 16x?

It's possible to run them in 16x/16x mode if you get an i7-6850K or better. But it usually doesn't make a significant difference to gaming performance, and it probably makes a lot more sense for most people to get a 7700K or 6800K.

[SnowyMus]

Each card needs at least 8 lanes. You most likely won't get a significant performance improvement (if any) with 16 lanes each over 8, but it's something to consider. If you do want 16 lanes each, get a 40-lane Intel CPU.

 

You'll need a motherboard that supports SLI. For Intel motherboards, you'll be looking for the Z chipset boards for mainstream and X99 for enthusiast. As for AMD, if you're getting Ryzen, X370 is what you're looking for. Otherwise, many 900 series chipset motherboards support it. Most motherboards with SLI compatibility will advertise so.

[App4that]

The 6850k and 6900k have 40 total lanes, enough for both cards to run at 16 each. Ryzen only has 16 lanes for graphics, so you will be at 8 lanes each.

[i_build_nanosuits]

19 minutes ago, paps511 said:

Not sure if this belongs under CPU or GPU, but I was wondering how many PCI lanes I would need to SLI 2 1080Tis? Is it possible to run them both at 16x? or would it even matter?

I plan on upgrading from my 4690k to either a 6800, 6850 or 6900.

 

I don't stream but I do a bit of development work

X8/X8 is perfectly fine you'll see no benefit from moving to X16/X16

Also, if you're only gaming you should consider a 4790K if you like your current board.

[App4that]

25 minutes ago, i_build_nanosuits said:

X8/X8 is perfectly fine you'll see no benefit from moving to X16/X16

Also, if you're only gaming you should consider a 4790K if you like your current board.

That's not entirely accurate. For gaming x8 per card is "fine", but if you're running multiple cards you have to ask if "fine" is what you really want. 

 

Agree with the 4790k recomendation though. 

[i_build_nanosuits]

Just now, App4that said:

That's not entirely accurate. For gaming x8 per card is "fine", but if you're running multiple cards you have to ask if "fine" is what you really want. 

 

Agree with the 4790k recomendation though. 

no...PCIE 3.0 X8 is PLENTY for ANY graphics card...any resolution...it's quite a bit more than you need.

[App4that]

1 minute ago, i_build_nanosuits said:

no...PCIE 3.0 X8 is PLENTY for ANY graphics card...any resolution...it's quite a bit more than you need.

There's that "plenty" again. When did we start to be so afraid of headroom? Sure a 1500w power supply is overkill for a 13 and 1050, but having enogh lanes isn't the same. 

[i_build_nanosuits]

Just now, App4that said:

There's that "plenty" again. When did we start to be so afraid of headroom? Sure a 1500w power supply is overkill for a 13 and 1050, but having enogh lanes isn't the same.

yes it's the same...having more will prove to be useless...at least until they launch GPU's twice as fast as a GTX 1080...GTX 1080 has been tested at pcie 3.0 X8 vs X16 and it doesnt change performance...not even 0.5%

[App4that]

Just now, i_build_nanosuits said:

yes it's the same...having more will prove to be useless...at least until they launch GPU's twice as fast as a GTX 1080...GTX 1080 has been tested at pcie 3.0 X8 vs X16 and it doesnt change performance...not even 0.5%

So all that matters is fps? Hmmm, that's why people complain about SLI. Stability mate, it matters. 

[paps511]

11 minutes ago, App4that said:

That's not entirely accurate. For gaming x8 per card is "fine", but if you're running multiple cards you have to ask if "fine" is what you really want. 

 

Agree with the 4790k recomendation though. 

 

39 minutes ago, i_build_nanosuits said:

X8/X8 is perfectly fine you'll see no benefit from moving to X16/X16

Also, if you're only gaming you should consider a 4790K if you like your current board.

I wouldn't upgrade to a 4790k. it would serve minimal improvement and is fairly old (in terms of computers at least) I'd be doing a major overhaul on my system.

 

Start with the GPUs and move on to CPU a few months later or more if there is talk about a 7800k

[App4that]

LOL, 4790k old. Ahhhh, we're old farts @i_build_nanosuits

[paps511]

3 minutes ago, App4that said:

LOL, 4790k old. Ahhhh, we're old farts @i_build_nanosuits

No, I mean it's not 'old' but If I am going to upgrade, its going to be substantial.

[App4that]

5 minutes ago, paps511 said:

No, I mean it's not 'old' but If I am going to upgrade, its going to be substantial.

A 4790k is withing spitting of a 7700k, anywhere. Even synthetics are close, real world they're closer. What offers the 7700k an advantage is DDR4, I have my DDR3 at 2400Mhz, not the 1600MHz most testing with the 4790k is done at. 

 

The 4790k is a much better built CPU, the PCB is so strong you delid a 4790k by putting the heat spreader in a vise and hitting the PCB with a soft hammer. Try that with a Skylake CPU and you're going to have a bad time LOL.

 

Optimization of Ryzen, or Intel answering AMD will bring a substantial upgrade. We just don't have one right now.