PCIe 3.0 Lanes with 2xGPU + Intel 750 PCIe Z97 vs X99

[iRiley]

I'm building a new system later this year, but thinking through my options at the moment and wanted some informed, constructive input.  

The system is going to be my "do everything" PC.  Gaming, Music/Video production & CAD

 

My original thinking was Z97 with a 4790k overclocked, 2x GTX980 in SLI with a 1 to 2TB STAT-III SSD (i have a NAS for my main storage), 32GB DDR3 PCI 2.0 audio interface. That's a decent system, right? The bottle neck is likely to be the SSD r/w speed. Maybe i could Raid 0, but then you have to consider redundancy as a potential drawback. But with the new PCIe SSD's coming over the horizon it is changing my thinking. If I'm spending that kind of money on a system that I want to do everything comfortably, should i consider PCIe storage? Which brings me to why i posted in this category.

 

My understanding of the way PCIe 3.0 traffic is handled through the chipset to the CPU is that it is shared through the available lanes. So that's 16Lanes on Z97, 41Lanes on X99.  With the Z97 that would mean there would be contention, but not on the x99.  If I go down the route of X99 I'm then seriouly ramping up the cost of the system: MoBo, RAM, CPU etc

 

I guess what I'm really asking is will I notice the contention of 2GPU & SSD on the 16 Lanes of the Z97? 

Does anyone have experience of both architectures?

At what level of cpu demand is x99 needed/advised?

Is high end multi GPU with PCIe SSD designed for X99 or is it suitable for Z97?

Will I get a better performing system with the GPU's sharing the 16Lanes of a Z97 and having a SATA III drive(s) or does the benefit of PCIe SSD out weigh the contention, even on the Z97/LGA1150 platform? 

[jaypro]

It obviously comes down to cost.  In my opinion the cost of upgrade from Z97 to X99 definitely does not warrant having your GPU run at a full 16x 16x.  With SLI graphics cards running PCI-E 3.0 8x 8x  will have minimal impact on your gaming.

 

www.youtube.com/watch?v=rctaLgK5stA, video discussing 16x vs 8x.

 

Go with Z97 unless you really need the CPU horsepower provided by X99.  Anybody who needs the CPU horsepower of the X99 chipset already knows they need it.  If you think you need it, you probably don't.

 

If you plan on spending the same money on Z97 vs X99, upgrades to other components will have a much bigger impacts than the platform.  A quick and dirty example of this would be 

 

Z97 + SLI 980Tis will cost similar to X99 SLI 980, and the first config will outperform the second for most use cases.

[NumLock21]

Go with the X99, you will not have enough PCIe lanes on the Z97 if you're planning to run dual video cards. Max number of PCIe lanes on socket 1150 is 16, Both video cards will used up all of the PCIe lanes from the CPU, leaving you none for the nvme ssd. Now If LTT's Nvme reviews is correct and it still lets you run the nvme ssd by using the lanes on the intel z97 pch, the ssd itself will not run at its full speed. Z97's M.2 is locked down at x2 mode. 

X99 starting with the Core i7 5930K has a total of 40 PCIe lanes, with 2 video card, even at full x16/x16 mode, it only uses up 32 lanes, this give you with 8 PCie lanes left for your Nvme ssds. Each nvme ssd full speed is PCIe 3.0 at x4. So with that you have have up to 2x NVMe SSDs.

Price differene isn't a lot between the Z97 and X99, depending on how you configure your components, it's about $100-$200 dollars.

16+16=32+4+4=40

 

With a 5820K is has 28 pcie lanes, some boards with dual video cards it runs it as it as x16/x8 that's 24 PCIe lanes used for the video cards. You'll have PCIe lanes left for 1x NVMe SSD. 16+8=24+4=28

[Maslofski]

Nvidia card will only run SLI ive in 8x, so 2 980s take up 16 lanes, leaving none to the SSD

[iRiley]

 

It obviously comes down to cost.  In my opinion the cost of upgrade from Z97 to X99 definitely does not warrant having your GPU run at a full 16x 16x.  With SLI graphics cards running PCI-E 3.0 8x 8x  will have minimal impact on your gaming.

 

www.youtube.com/watch?v=rctaLgK5stA, video discussing 16x vs 18x.

 

Go with Z97 unless you really need the CPU horsepower provided by X99.  Anybody who needs the CPU horsepower of the X99 chipset already knows they need it.  If you think you need it, you probably don't.

 

If you plan on spending the same money on Z97 vs X99, upgrades to other components will have a much bigger impacts than the platform.  A quick and dirty example of this would be 

 

Z97 + SLI 980Tis will cost similar to X99 SLI 980, and the first config will outperform the second for most use cases.

 

I agree, Z97 was the side I came down on, but how is the performance affected when you bring PCIe 3.0 SSD into the mix?  Does the 4Lanes used on the SSD have a serious performance drag on the PCIe bus and therfore would SATA be better in this Z97 scenario?   Or is the PCIe interface so mega that even with 3 devices of 20lanes competing over 16Lanes of Z97 still the superior option?

[FruitBasketSilex]

Why not get a z97 board with a plx switch so that you get more lanes without having to go x99?

[Elapo]

I agree, Z97 was the side I came down on, but how is the performance affected when you bring PCIe 3.0 SSD into the mix?  Does the 4Lanes used on the SSD have a serious performance drag on the PCIe bus and therfore would SATA be better in this Z97 scenario?   Or is the PCIe interface so mega that even with 3 devices of 20lanes competing over 16Lanes of Z97 still the superior option?

 

If you place that SSD in there, the speeds of the other lanes will be reduced, because you'd exceed the maximum (8+8+1 = 17 > 16)

 

This means that both GPUs will run at 4x when you add a 1x card ( to stay within spec, so you'll end up with 4+4+1=9). Not sure, but an SLI setup might not like this, as one of the requirements for SLI is that the GPUs should run at 8x. Crossfire will most likely work though. It's not a bandwidth issue, it's just not supported by SLI.

[iRiley]

My understanding was wrong then,  it's not that there is contention, the system slows the other PCIe devices to accommodate the lane usage.

I'm thinking that PCIe SSD wasn't meant for Z97.  Even if I went with a single GPU, eg 980ti with SSD,  that would then be running at 8x due to the SSD.

 

Some LTT benchmarks on this would be interesting. To quantify the performance difference

 

z97

single GPU with SSD

single GPU with SSD raid 0

single GPU with PCIeSSD

dual gpu with PCIeSSD

 

x99

dual gpu with PCIeSSD

 

We may then see what the true purpose of x99 is. I think disk drive r/w speed could be one of the reasons that there doesn't seem to be much of a performance difference when you compare the two platforms

[FruitBasketSilex]

My understanding was wrong then, it's not that there is contention, the system slows the other PCIe devices to accommodate the lane usage.

I'm thinking that PCIe SSD wasn't meant for Z97. Even if I went with a single GPU, eg 980ti with SSD, that would then be running at 8x due to the SSD.

Some LTT benchmarks on this would be interesting. To quantify the performance difference

z97

single GPU with SSD

single GPU with SSD raid 0

single GPU with PCIeSSD

dual gpu with PCIeSSD

x99

dual gpu with PCIeSSD

We may then see what the true purpose of x99 is. I think disk drive r/w speed could be one of the reasons that there doesn't seem to be much of a performance difference when you compare the two platforms

Just get a z97 board with a plx chip?

And x8 doesn't affect GPU performance.

[iRiley]

Just get a z97 board with a plx chip?

And x8 doesn't affect GPU performance.

x8 doesn't affect GPU performance.... at all???

[FruitBasketSilex]

x8 doesn't affect GPU performance.... at all???

At all.

(Assuming pcie3, I don't Sven think 3.0 x4 affects performance.

[TechSilver13]

A Z97 PLX board will run you more than a budget X99 board will.

 

Z97 PLX Board - $212

http://www.newegg.com/Product/Product.aspx?Item=N82E16813157527&cm_re=asrock_z97_extreme9-_-13-157-527-_-Product

 

DDR3 - $116

http://www.newegg.com/Product/Product.aspx?Item=N82E16820231673&cm_re=ddr3_16gb-_-20-231-673-_-Product

 

4790K - $325

http://www.superbiiz.com/detail.php?name=I7-4790KBX&c=CJ

 

Total - $653

 

X99 Mobo - $229

http://www.newegg.com/Product/Product.aspx?Item=N82E16813130796&cm_re=x99_motherboard-_-13-130-796-_-Product

 

DDR4 - $159

http://www.newegg.com/Product/Product.aspx?Item=N82E16820233727&cm_re=ddr4_16gb-_-20-233-727-_-Product

 

5820K - $389

http://www.newegg.com/Product/Product.aspx?Item=N82E16819117402

 

Total - $777

 

It is a 124 dollar difference to go X99.  Do it right and go X99, if you have a MircoCenter near by it will be even cheaper (over a hundred dollars less than $777)

 

 

And from MY EXPERIENCE (mine, not everyone else) I had a Z97 Maximus 7 Hero/4790K/DDR3 2400/dual 980 Classifieds/Creative ZxR/Asus Wifi PCIE card and had laggy game performance (especially of GTA V, my audio would start to pop, and my wifi went from 1300mps down to double digits because my PCIE lanes were TAPPED out.  Keep in mind that its not always about running your cards 16x by 16x as 8x doesnt change performance as stated earlier but if you are indeed plugging all that into your motherboard you will run into problem.  All of my problems were resolved after upgrading to X99 and getting 40 PCIE lane (5930K) instead of 16 lanes from Z97.  If it's between a PLX Z97 board and X99, I think its a no brainer.

[iRiley]

A Z97 PLX board will run you more than a budget X99 board will.

 

Z97 PLX Board - $212

http://www.newegg.com/Product/Product.aspx?Item=N82E16813157527&cm_re=asrock_z97_extreme9-_-13-157-527-_-Product

 

DDR3 - $116

http://www.newegg.com/Product/Product.aspx?Item=N82E16820231673&cm_re=ddr3_16gb-_-20-231-673-_-Product

 

4790K - $325

http://www.superbiiz.com/detail.php?name=I7-4790KBX&c=CJ

 

Total - $653

 

X99 Mobo - $229

http://www.newegg.com/Product/Product.aspx?Item=N82E16813130796&cm_re=x99_motherboard-_-13-130-796-_-Product

 

DDR4 - $159

http://www.newegg.com/Product/Product.aspx?Item=N82E16820233727&cm_re=ddr4_16gb-_-20-233-727-_-Product

 

5820K - $389

http://www.newegg.com/Product/Product.aspx?Item=N82E16819117402

 

Total - $777

 

It is a 124 dollar difference to go X99.  Do it right and go X99, if you have a MircoCenter near by it will be even cheaper (over a hundred dollars less than $777)

 

 

And from MY EXPERIENCE (mine, not everyone else) I had a Z97 Maximus 7 Hero/4790K/DDR3 2400/dual 980 Classifieds/Creative ZxR/Asus Wifi PCIE card and had laggy game performance (especially of GTA V, my audio would start to pop, and my wifi went from 1300mps down to double digits because my PCIE lanes were TAPPED out.  Keep in mind that its not always about running your cards 16x by 16x as 8x doesnt change performance as stated earlier but if you are indeed plugging all that into your motherboard you will run into problem.  All of my problems were resolved after upgrading to X99 and getting 40 PCIE lane (5930K) instead of 16 lanes from Z97.  If it's between a PLX Z97 board and X99, I think its a no brainer.

Thanks for your input.  A good point that the human experience is often something that doesn't get benchmarked sound quality may get missed in a graphic benchmark and real world factors e.g wifi affect performance too.  

 

What about a drop to 4x which would be the case if I were on Z97 with dual GPU and PCIe SSD.  Would that be noticeable? Would that performance be worse than Dual GPU at 8x and a Sata3 SSD?

[Elapo]

Thanks for your input.  A good point that the human experience is often something that doesn't get benchmarked sound quality may get missed in a graphic benchmark and real world factors e.g wifi affect performance too.  

 

What about a drop to 4x which would be the case if I were on Z97 with dual GPU and PCIe SSD.  Would that be noticeable? Would that performance be worse than Dual GPU at 8x and a Sata3 SSD?

 

Seeing as 4x Gen3 is the same as 8x Gen2, and I'm running SLI 970 with a 2600k (which only supports Gen2 AFAIK) without an issue, I'd say running your cards at 4x isn't a problem, given you're using PCIe Gen3.

[Sebastian]

What about a drop to 4x which would be the case if I were on Z97 with dual GPU and PCIe SSD.  Would that be noticeable? Would that performance be worse than Dual GPU at 8x and a Sata3 SSD?

 

I think you're getting hung up on the 4x vs 8x. To summarize what other people in this thread have already said:

 

• For a single card, performance will be identical whether it's running at PCIe 3.0 x16, x8, or x4. So don't worry about that.
• For SLI to be enabled, each card needs to run at either x8 or x16. If one or more cards is at x4, you won't be able to turn on SLI.
• Z97 has 16 total lanes, which means that if you want to run dual cards in SLI, the only option is for them to both run at x8. This means that if you run SLI on Z97, you will not be able to put in anything else in a PCIe 3.0 slot, Period.
• The only possible way to use two or more cards in SLI AND a PCIe 3.0 SSD is to use X99.

[NumLock21]

Seeing as 4x Gen3 is the same as 8x Gen2, and I'm running SLI 970 with a 2600k (which only supports Gen2 AFAIK) without an issue, I'd say running your cards at 4x isn't a problem, given you're using PCIe Gen3.

You cannot apply pcie lanes by gens, it does not work. sli requires the slot to either run at x16 or x8. Doesn't matter if it's pcie 3.0 or 6.0

[Sebastian]

You cannot apply pcie lanes by gens, it does not work. sli requires the slot to either run at x16 or x8. Doesn't matter if it's pcie 3.0 or 6.0

 

I think all he meant was that PCIe 3.0 x4 has the equivalent bandwidth of PCIe 2.0 x8. The point was that the bandwidth of PCIe 3.0 x4 would not limit the performance of a modern GPU. The fact that it wouldn't work for SLI is a separate point.

[Elapo]

You cannot apply pcie lanes by gens, it does not work. sli requires the slot to either run at x16 or x8. Doesn't matter if it's pcie 3.0 or 6.0

 

The post I replied to was talking about bandwidth, I've said before SLI requires 8x anyway.

I was pretty much saying this:

I think all he meant was that PCIe 3.0 x4 has the equivalent bandwidth of PCIe 2.0 x8. The point was that the bandwidth of PCIe 3.0 x4 would not limit the performance of a modern GPU. The fact that it wouldn't work for SLI is a separate point.

[Stefan1024]

- snip -

You can hook up the NVMe PCI-E SSD on the PCI-E 2.0x4 interface.

That's the way I squeeze the most performance out of the Z97. Howerver with an Intel 750 you will locked down to ~1GB/sec write (instead on 1,3) and ~1,5GB/sec read (instead of 2,7) look here: http://linustechtips.com/main/topic/368455-intel-750-on-pci-e-20x4-still-worth-it/

But you will still benefit from the IOPs of NVMe.