Mobo PCIe optimisations

porina · November 9, 2017

In short, I have an Optane 900p due to arrive tomorrow. Do I connect it to a PCIe slot off the CPU, but this will limit my GPU to x8, or connect it to a PCIe slot off chipset? TBH I don't really care about sequentials that much, as I bought the 900p for random read speed. I don't think connecting it off the chipset lanes will impact transfer rates, unless there is a measurable reduction in latency if I use the CPU lanes? I need to measure it, but I wonder if there is a noticeable effect to dropping the GPU to x8...

System is 1st in sig, but key points are:

Asus Maximus Hero VIII (Z170), 1080Ti, existing M.2 NVMe* SSD which will remain for boot.

_{*it is actually AHCI but no one seems to have ever heard of those For practical purposes it is like NVMe, not SATA.}

#firstworldproblems

Trulop · November 9, 2017

going from x16 to x8 really doesnt change much for performance, so you should be just fine. As far as i know, it is better to go directly through the CPU to get a faster result in some cases, but in terms of storage, unless your doing some heavy file transferring or something that can utilize insane speeds, a simple sata SSD will be more than enough for majority of programs and games as they cant really use the insane speeds of NVME anyways and i dont really know how much the impact would be if much at all.

So either way i dont think it will really matter.

Any others opinions?

Oshino Shinobu · November 9, 2017

Ultimately, it will make no negative impact regardless of what you do. The GPU running at 8X won't limit its performance and the SSD running off the chipset won't limit the SSD's performance.

I'd personally just run it off the chipset. It has plenty of lanes to spare and it would allow another GPU to be added later if you wanted.

EDIT: If you want my opinion on the 900p itself, I'd say it's a massive waste of money. It won't improve boot, OS, game or pretty much any everyday use case. Random read/writes isn't what NVMe is good at (it still is, but makes no real world difference compared to AHCI), it's sequential read/writes. So if you're copying large files a lot or loading large projects into RAM, NVMe is good. For basically everything else, it's on par with a normal SATA SSD.

Intel seems to be marketing the SSD towards "eSport Gamers" or at least using that as a way to sell it. Seems bizarre when games are one of the applications where it makes some of the least difference.

NVMe drives make excellent scratch disks, but that's about it IMO. It's not worth the cost to buy a large one or have one as your primary drive.

porina · November 9, 2017

11 minutes ago, Trulop said:

a simple sata SSD will be more than enough for majority of programs and games as they cant really use the insane speeds of NVME anyways and i dont really know how much the impact would be if much at all.

That's the thing. I've installed games on a "regular SATA SSD" due to lower cost, and I do think it is holding me back a bit.

11 minutes ago, Oshino Shinobu said:

EDIT: If you want my opinion on the 900p itself, I'd say it's a massive waste of money. It won't improve boot, OS, game or pretty much any everyday use case. Random read/writes isn't what NVMe is good at (it still is, but makes no real world difference compared to AHCI), it's sequential read/writes. So if you're copying large files a lot or loading large projects into RAM, NVMe is good. For basically everything else, it's on par with a normal SATA SSD.

I'm willing to try it out, as the cost is not really significant to me. I suspect that low QD random reads are holding us back more than we think, in a similar way that was the driving difference between HDs and SSDs. Now, I'm lazy so I'm not going to re-install my main system just to find out, but by adding it as a secondary drive I can still install other important things on it and see what difference it makes. I have done pre-testing using a ramdisk and that suggested I might be looking at around 30% reduction in load times in FFXIV which is pretty much what I care about at the moment. I do have enough sanity not to get a ton of ram just to make a ramdisk for it! Not at current ram prices anyway...

11 minutes ago, Oshino Shinobu said:

It's not worth the cost to buy a large one or have one as your primary drive.

I'm in an awkward spot in that sense. I almost got the cache versions to use as a storage device, but I'd need two 32GB units in raid 0 to make the needed capacity and that seemed too messy. Now the 280GB is out at better cost/capacity, but I don't need all that either. If they did a hypothetical 120GB version at half the cost of the 280GB model that would have been about perfect.