Benefit of Z270 PCI-E lanes

[pantsaregood]

So, the PCI-E lane count on the chipset is being bumped to 24 from 20. I'm not quite sure how this is useful, however.

Let's say someone has a Z170 board where all 20 chipset-based lanes are in use and four of those are being used for an extremely fast NVMe SSD. The owner of the board decides he wants another NVMe SSD in the M.2 form factor, so he purchases one with Z270 motherboard and puts them in RAID 0.

This is the part that loses me - the connection between the chipset and CPU has the bandwidth of PCI-E x4, so throwing those NVMe drives into a RAID 0 should presumably do nothing due to being bottlenecked by the CPU-chipset bandwidth.

What am I missing?

 

[Insert_Nickname]

What am I missing?

Nothing. If you're interested in RAID'ed SSDs you either:

1) Take 8 lanes from the CPU and hook one directly to the CPU. The disadvantage is that you cannot use Intel RST for this, since drives have to be connected to the PCH. I don't know if there are any consumer boards that allow you to do an 8x/4x/4x configuration from the CPU, that would be the optimal configuration of course.
2) Move to the HEDT platform.

As a side note I don't think SSDs in particular are a problem, but connecting a 10Gbit Ethernet card, an Alpine Ridge USB 3.1 controller and an SSD could become problematic.

 

[Valantar]

As a side note I don't think SSDs in particular are a problem, but connecting a 10Gbit Ethernet card, an Alpine Ridge USB 3.1 controller and an SSD could become problematic.

Only if you actually stress them all consistently and simultaneously. Which isn't going to happen in a consumer build.

The only real benefit I see from this is that users with a single NVMe SSD will be able to add another (as a games drive or whatever) a couple of years down the line when the first one is starting to feel cramped without a full reinstall or drive clone (which would require two m.2 slots anyway).

 

[BonzaiDuck]

Hmm. I could continue to wonder if my "great pending experiment" will have a fly in its ointment. I'm not going to use my first M.2 NVMe for "storage."

 

[Insert_Nickname]

Only if you actually stress them all consistently and simultaneously. Which isn't going to happen in a consumer build.

Not right now, but I'd hate to think of the bandwidth required for 8K video. Uncompressed 4K is already pushing ~700MB/s.

I've never believed in being interface limited.

 

[Valantar]

Not right now, but I'd hate to think of the bandwidth required for 8K video. Uncompressed 4K is already pushing ~700MB/s.

I've never believed in being interface limited.

Who on earth who actually needs to work for any real length of time with 4k/8k video is doing this on a non-HEDT platform? That's beyond dumb. And Intel's HEDT platforms have 28/40 lanes, which is plenty for a GPU, TB3 and whatever SSDs you want/need.

"Switched" lanes through the PCH are good enough for >99% of consumer usage. For now. Hopefully, they'll move to 24 lanes (with more splitting options) from the CPU and an 8-lane link to the PCH some time in the not too distant future. But I'm not holding my breath.

 

[Insert_Nickname]

Who on earth who actually needs to work for any real length of time with 4k/8k video is doing this on a non-HEDT platform?

Given the exact same platform is used for laptops, you may be surprised.

 

[Valantar]

Given the exact same platform is used for laptops, you may be surprised.

Well, if that's the case, they're already CPU limited in pretty much everything, so what does it matter if IO is less than ideal? And especially in a laptop, you wouldn't be able to tax both one or two high end SSD and TB3 to such a degree that the CPU-PCH link is an issue. And 10GBE is nonexistent in the mobile space. None of these are actual issues.

 

[Insert_Nickname]

I think we're somehow talking past one another. None of this is an issue right now, but 2 or 5 years down the line? Given the very slow progress of CPU performance, and the number of users using older computers out there, and the fact we will not see an increase in bandwidth until at least Icelake (>2018), perhaps even Icelakes successor, this is a concern if you're looking to future proof. I can already saturate the DMI 2.0 link on my own primary system, the same will happen to DMI 3.0 eventually.

I'm also just looking at this from the consumer side, professionals will (usually... ) have access to the required equipment.

Well, if that's the case, they're already CPU limited in pretty much everything, so what does it matter if IO is less than ideal? And especially in a laptop, you wouldn't be able to tax both one or two high end SSD and TB3 to such a degree that the CPU-PCH link is an issue.

The high-end quad core mobile Skylake chips doesn't perform that much worse then their desktop counterparts, if you exclude the 6700K/7700K. They are perfectly capable of benefiting from every IOPS you can squeeze from the storage system. We already have SSDs that are capable of saturating a PCIe 3.0 x4 link all by themselves. This is even more an issue in laptops which usually only have a single storage drive, hence R/W will happen at the same time. On the desktop you can just add a few additional drives for scratch-pad or encoding.

People do use high-end laptops for on-the-spot editing, and use a dock when they get back home. Desktops aren't as common as one might think any more. Since the platforms are more-or-less shared, neither can progress without the other.

Then there are the people who simply cannot afford the buy-in to the HEDT. But still want to edit video. Buying both a reasonable laptop and a HEDT PC will set you back a significant amount. Most will prefer their laptop, since it is more flexible.

And 10GBE is nonexistent in the mobile space. None of these are actual issues.

We'll soon see both 2.5Gbit and 5Gbit Ethernet, perhaps even some Kaby Lake laptops will feature it. And when there is already a 40Gbit TB3 controller, a 10Gbit Ethernet option doesn't seem that far fetched.

 

[phillyman36]

Only reason I want a z270 is to use 2 Nvme ssd (not in raid). I only use one gpu. A Samsung 960 for the os and a Samsung 950 as a sort of scratch disk for my video/blu ray converting.