Deciding between x99 and z170

[Shadowwrath5]

Hello! I'm going to upgrade to a new pc soon because it looks like the tech has slowed down a bit and my purchase won't be dated in a week
Anyway I'm having trouble decking between x99 and z170. My main concern is that I'm going to include two 980ti's in sli, a 10gb nic, and Intel's new pci ssd as my boot drive. I'm worried that skylake just doesn't have the lanes to handle everything at optimal speeds. Should I be worried or should I go for the 40 lanes of z170 platform? Is skylake going to get a 40 lane cpu? Thanks!

 

[G-star93]

I would go with x99 again i sold my i7 6700 and want it something faster and i was deciding between 6700k and 5820k and went for x99 and im not sorry. 6700k was waaay overpriced and 5820k was cheaper but mobos for x99 are a little bit more expensive

 

[Shadowwrath5]

But what about the avalible lanes? I don't perform too many cpu heavy tasks daily but I want to make sure I'm not bottle necking my cards or pci ssd or nic due to the amount of avalible lanes

 

[Sakkura]

Well, the Z170 chipset has more PCIe lanes than the X99 chipset, whereas the Skylake CPU itself has fewer PCIe lanes than the Haswell-E CPU. So it's more of a tradeoff than a clear upgrade either way.

The main problem of Z170 is the DMI 3.0 connection between the chipset and the CPU. You can plug tons of stuff into the chipset, but if all of that stuff is transmitting tons of data then the connection between chipset and CPU will bottleneck things.

You can't plug nearly as much into the X99 chipset, but then the risk of a bottleneck on its slower DMI 2.0 connection to the CPU is also that much smaller. Instead you can plug more stuff directly into the CPU. But that's still somewhat more limited than relying on the chipset. Not too many X99 boards come with triple M.2 slots capable of running PCIe 3.0 x4, for example.

 

[Shadowwrath5]

So in short wish for a 40 lane skylake or deal with the performance loss either way?
In this situation if I had to take the loss, then go with skylake anyway because it could fair better between the two.

 

[G-star93]

But what about the avalible lanes? I don't perform too many cpu heavy tasks daily but I want to make sure I'm not bottle necking my cards or pci ssd or nic due to the amount of avalible lanes

6700k has 20 pcie lanes, 5820k has 28 pcie lanes, 5930k and 5960x has 40 pcie lanes. 5820k is enough for 2 and 3 way Sli/crosfire configuration

 

[Sakkura]

So in short wish for a 40 lane skylake or deal with the performance loss either way?
In this situation if I had to take the loss, then go with skylake anyway because it could fair better between the two.

There won't be a 40-lane Skylake CPU, at least until Skylake-E arrives (2017?)

@G-star93, the 6700K has 16 PCIe lanes, not 20.

 

[Shadowwrath5]

2 lane sli, a nic and a pci ssd?

 

[G-star93]

So in short wish for a 40 lane skylake or deal with the performance loss either way?
In this situation if I had to take the loss, then go with skylake anyway because it could fair better between the two.

There won't be a 40-lane Skylake CPU, at least until Skylake-E arrives (2017?)

@G-star93, the 6700K has 16 PCIe lanes, not 20.

my bad, then that's even worse lol

 

[G-star93]

go for x99

 

[Shadowwrath5]

Thanks!

 

[Sakkura]

2 lane sli, a nic and a pci ssd?

There shouldn't be any major difference between X99 and Z170 with that with current hardware, but if you got an even faster SSD than currently available options like the Samsung 950 Pro, then along with the 10 gigabit NIC you could (in rare situations) bottleneck the DMI a little bit on the Z170 platform.

 

[Shadowwrath5]

Sorry to add to my question, but what about motherboards with a plx chip? I don't really understand how this works but if I found one on a skylake board wouldn't that help? Doesn't it enable the lanes to run at full speed without needing a bunch of lanes?

 

[Sakkura]

A PLX chip works similarly to the chipset. It has a given PCIe connection to the CPU, and then provides more lanes (twice as many, usually) to the devices plugged in. But if everything's transmitting data simultaneously it will still be bottlenecked by the connection to the CPU.

The extra lanes help getting SLI to work (given that Nvidia requires 8 lanes to each card), but might not always provide optimal performance, at least in theory. It doesn't magically create more bandwidth, just shares it around better.

 

[Shadowwrath5]

Alright last question. What about that 4 lanes dedicated to memory. Why can't we use them. Or can we?

Is there ever going to be a true 20 lane skyline? 28? We probably just won't know.

 

[Sakkura]

Alright last question. What about that 4 lanes dedicated to memory. Why can't we use them. Or can we?

Is there ever going to be a true 20 lane skyline? 28? We probably just won't know.

The "lanes" to memory are not PCI Express lanes, so they only work with the particular type(s) of memory the memory controller is designed for.

Mainstream Skylake won't get any CPUs with more PCIe lanes, at least I'm 99.99% sure of that. Skylake-E will. Might be 40 lanes for the top of the line and 28 lanes on a cheaper version, the way it is right now with the Haswell-E CPUs. Or Intel might change it around. Intel may also move to PCIe 4.0 by then.