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ROG RAMPAGE VI EXTREME PCIe lanes distribution and Intel Optane 905p PCIe x4 support

Zhora_007
Level 8
Hi!

In present reality of enthusiast hardware pricing and complexity, the value of correct new build planning is hard to overestimate. Though, it is very sad that necessary information critical for proper system planning is very hard to find and hardware vendors are mostly silent.

One of such critical and confusing subject, based on the number of threads in many forums, is the correct PCIe lanes and slots configuration for particular motherboards, especially X299 based.

To make a long story short, is this configuration possible and operatable with ASUS ROG RAMPAGE VI EXTREME with Core i9-7900X?

- PCIex16/x8_1: ASUS Hyper M.2 x16 card with four Samsung 2TB 960 Pro PCIe x4 SSD's for non-bootable VROC RAID0 storage - in x16 mode (to enable 4 M.2 SSD's in x4 mode each);
- PCIex8_2: GPU1 (1080Ti) - in x8 mode;
- PCIex16/x8_3: GPU2 (1080Ti) - in x8 mode;
- PCIex8_4: Intel Optane 905p PCIe x4 SSD for the OS - in x4 mode.

I am totally fine with both VGA cards in SLI at x8.

Am I correct that in the above case all PCIe slots and lanes are all CPU sourced and correspond to PCIe mode mentioned in the R6E manual (x16/x8/x8/x8 with 44-lane CPU)?

Also confused with the R6E manual about Optane support: "Intel Optane technology is only supported by M.2_1 when sourced from the PCH",- does that mean that PCIe x4 version of 905p will only be supported via PCIex4_1 which is sourced, supposedly, from the PCH or not supported at all, so the smaller U.2 version should be used?

Thank you for help!

P.S.: It would be great if ASUS were the first vendor to introduce detailed and clear guidelines about PCIe lanes configuration and possibilities, showing care about their consumers, as the price of incorrect planning is becoming more and more expensive and this subject is not as self-explanatory from the manuals as it might seem even for experienced...
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13 REPLIES 13

Korth
Level 14
I don't own that board so I'm not sure if it's compatible with your suggested lane configuration.

But I am curious about what kind of task/workload your build is meant to optimize, that's a lot of fast storage and a lot of priority on fast storage. As you say, this sort of hardware is not inexpensive, so I'm guessing you've shortlisted these specific parts with a very specific purpose in mind.

And I'm curious why you think an Optane cache drive will be better/faster (as your system drive) than another Samsung 960/970/etc.
"All opinions are not equal. Some are a very great deal more robust, sophisticated and well supported in logic and argument than others." - Douglas Adams

[/Korth]

Zhora_007
Level 8
Thank you for the question!

Idea behind picked hardware and the build is quite simple - to squeeze maximum no-compromise performance from each sub-system: both graphics and storage what they were dedicated for.

Firstly, PCIe x8 bandwith per each graphics card is enough in real-world gaming scenarios, even most demanding ones (https://www.gamersnexus.net/guides/2963-intel-12k-marketing-blunder-pcie-lane-scaling-benchmarks).

What was really always interesting for me is to have simultaneously dedicated storage subsystem to match the highest performance. IMO, storage system has always been a bottleneck in building no-compromise system. Though with the launch of X299 ecosystem it becomes finally possible at consumer level.

X299 goodies out of the box like VROC, bifurcation support together with Hyper M.2 x16 PCIe splitter card makes some exotic storage configurations possible, despite restrictions like Intel M.2 modules only for bootable arrays. Though, analysis shows that such bootable RAID0 configurations have even negative impact for OS drive performance comparing to single NAND-based PCIe x4 M.2 drive.

This happens, as I assume, as a result of decreased low queue depth performance which matters for OS workload real-world performance and is really visible in daily experience. That is why Intel Optane 905p with unmatched performance at low queue depths and latecies is currently the best option for OS drive, while VROC RAID0 on Samsung's fastest and largest 2TB NAND-based M.2 SSD with extreme sequential speed is the best option for data storage. That is my opinion.

Korth
Level 14
Agreed, x8 GPU and x8/x8 multi-GPU is plenty for even the most demanding of today's real-world games. There are actually instances where x16 GPU and x16/x8 (presumably also x16/x16) multi-GPU proves better, extreme instances where fps metrics are largely synthetic, but I think being able to reach these thresholds today is a sign of where things are going in hardware and software demands of the future.

I don't really agree that storage speed is a "compromise" anymore. I don't think it has been (with high-end hardware) since about early 2015. The performance advantages of fast storage are largely wasted in real-world (consumer) applications, and the sort of fast storage array you describe would be very difficult indeed to saturate without running tons of simultaneous hard-data hard-crunching virtual machines. Especially if you install the usual enthusiast allotment of 32GB~128GB (or more) physical RAM, doubly so if you allocate a good chunk of this RAM towards dedicated storage caching. I think the real performance bottleneck on this sort of "no compromise" system will actually be your processor (and also the chipset, to a lesser degree), even though they're basically the best stuff available at this time. Certainly better and faster hardware is always going to be better and faster hardware, I'm not saying that you wouldn't enjoy performance advantages, I am saying that I suspect there's various diminishing returns which will make these advantages much less spectacular than expected.

I'm flat out skeptical about the Optane 905p. Previous Optane products have been terribly overpriced and terribly underwhelming, much inferior to their M.2/NVMe (4xPCIe3) SSD counterparts, very disappointing. And there's very few online tests/comparisons/reviews available at this time for this new Optane, not enough "unbiased" data (yet) for me to decide what's fact and what's hype. I might be wrong (I kinda hope I am), but I seriously expect Optane 905p will be as disappointing (especially to tech-savvy gamers) as every previous Optane.

That being said, there are some niche applications where Optane proves to be superior to any alternative. Specialized high-hardware niches with heavy real-time data workloads, production video editing on Adobe Premiere (with workstation GPUs and JTAG2000 GPU Accelerators) is one such niche, massively complex and detailed (and animated) Autodesk and SolidWorks projects (with all the CPU cores and GPU cards you can pack) are another - and these run on platforms which don't just stuff an Optane onboard but carefully place Optane caching alongside other system drives. Admittedly, Intel's 3D XPoint (aka Micron QuantX) memory has seen numerous incremental improvements/refinements since first Optane launch in 2015, so maybe it's finally reached a tipping point where it can become more viable than other NVRAM technologies in a wider range of application models. It's just too early to tell, in my (skeptical and hopefully wrong) opinion.

And, back to my first point, most real-world performance of today's storage systems already exceeds most real-world demands on today's storage systems, there's little real difference between the top-tier products other than their prices and their synthetic benchmark scores. Even the most stalwart enthusiast has to question his sanity when the deciding parameter is a balance between massively inflated costs and slightly inflated benchmark scores.

Still, I'm also a computing enthusiast and I always love seeing other computing enthusiasts push the boundaries. Regardless of your results (which are hopefully impressive), your benchmarks could provide valuable data in influencing my own hardware selections.

You might want to check out Seagate Nytro XP7200 and HighPoint Intros SSD7101 - although both will be a little hard to obtain through consumer channels for a while. I still use a few good olde Comay Enterprise BladeDrives because they're 8xPCIe2 cards so they're easy to plug into "empty slots" on almost any platform with fully populated PCIe3 lanes.
"All opinions are not equal. Some are a very great deal more robust, sophisticated and well supported in logic and argument than others." - Douglas Adams

[/Korth]

Zhora_007
Level 8
Thanks! Obviously you are right in many aspects and unfortunately only some of them I can check in real, for the rest a theory and benchmarks are the only source)

Generally your value-for-money point is absolutely valid, but for enthusiasts "pushing the limits" is the value itself 😉

Anyway, I think that such basic information as clear PCIe lanes configuration and its application should be available without problems, if vendors are going to upsale their customers, but for whatever reason it is not.

Dronson
Level 7
Exactly same question. I cant turn on my 905p via u.2 connector. I cant understood how i must configure bios for activate u.2 port. Spend around one day for experiments without result ((. Documentation absolutely non transperent with this aspect.

I will be grateful for any help.

Seems like I finally managed to receive final reply from Asus technical support. So,

U.2 slot will share bandwith with m.2_1
PCIe 3.0 x4 - comes from chispet ( you can use it for optane but we strongly recommend use optane on U.2 )

Below is how we imagine your MB build
_________
PCIe x16_1 - goes for Hyper adapter with m.2 PCIe x4*4
( for VROC you also need to buy special key from intel for using raid 1,5,10 )
_________
PCIe x8_2 + PCIe x8_3 - will take your 2 GPU's with PCIe x8*2
_________
Intel optane will be with U.2
_________
For Intel Optane 905p PCIe card version, PCIe x8_4 will use last 8 lines of PCIe, and you can use it for connect intel optane card.

Dronson
Level 7
Thanks for your answer Zhora.

Now im have Optane 905 u.2. But i cant understood how im must setup bios settings for use this device.
I cant see my optane in bios or win10 installation menu (

Where in bios i can select option, for use pcie 3.0 x4 from chipset ?? (

The problem is I do not have MB and bios in front of me, but you can try the following: while in bios, press F7 to go into Advanced menu, in submenu «Onboard device configuration» and «М.2_1 source selection» option set «From PCH», and option «PCIEx8_4» set to «Auto»

Dronson
Level 7
Thankyou again!

Of course im try this options- does not matter, u.2 is unavaiable. May be i have failure mobo or optane (( or u.2 cable.