Something I've noticed with new Intel motherboards/chipsets

bobkn · Jan 30, 2023

hdmi said:
Have you verified that the PCIe bandwidth drops to PCIe Gen 4 x8 speed by running the PCIe bandwidth benchmark of 3DMark? Also, in GPU-Z when you run the little benchmark test from the window that opens after you click on the question mark button next to Bus Information, what does the Bus Information say?

With an M.2 card in M.2_1 (the CPU driven one), CPU-Z indicates that the graphics slot is limited to X8.

The link speed is shown as 2.5GT/s at idle. The little Render test in GPU-Z takes it up to the max, 16GT/s. That was true when the graphics slot was limited to X8, and it's still true at X16.

I don't recall whether I ever did an X8/X16 graphics comparison. Some online reviews showed a slight difference with my graphics card. (A few percent in gaming, variable depending on the game.)

BrianInEngland · Jan 31, 2023

bobkn said:
While PCI-E 5.0 nominally has twice the bandwidth of PCI-E 4.0, I am unaware that any board has the provision of duplexing X16 PCI-E 5.0 lanes into two X16 PCI-E 4.0 ones. (That's a pity, as there are no PCI-E 5.0 graphics cards at this time, AFAIK. The highest end ones are still Gen 4.)

If I use an M.2 drive in M.2_1 of my Asus RoG Strix Z690-E, the lanes available got the graphics slot fall back to X8, regardless of the PCI-E generation of the M.2 drive.

Asus makes boards which use the CPU's Gen 4 lanes for the M.2 slot. The graphics slot gets X16 regardless whether the CPU M.2 slot is populated or not.

The story is the same for Z690 and Z790 boards.

Exactly the point of my original post! Intel boards with Gen 5 M.2 slots CANNOT by design run a GPU at x16 if the G5 M.2 slot is used. The CPU only supports 16 G5 lanes so if they're connected to the first GPU slot there are no spare lanes for a Gen 5 M.2. All the PCI lanes are connected as G5 so it won't matter what gen the components are.

It's an either/or situation as I said initially - either x16 GPU or Gen 5 M.2, but not both at once.

BrianInEngland · Jan 31, 2023

hdmi said:
I am utterly shocked about a lot of things TBH. For example, if I can assume that the main goal is to play demanding games on high settings, then things like P2W, boring DLC and relentless cheating/laming in online multiplayer limits the usefulness to somewhere deep below zero for me so, I quit gaming altogether, like, more than a whole decade ago.

Point made but completely irrelevant to this thread!

bobkn · Jan 31, 2023

BrianInEngland said:
Exactly the point of my original post! Intel boards with Gen 5 M.2 slots CANNOT by design run a GPU at x16 if the G5 M.2 slot is used. The CPU only supports 16 G5 lanes so if they're connected to the first GPU slot there are no spare lanes for a Gen 5 M.2. All the PCI lanes are connected as G5 so it won't matter what gen the components are.

It's an either/or situation as I said initially - either x16 GPU or Gen 5 M.2, but not both at once.

Sorry to be redundant. I was replying to a particular post, although my statements were general.

BrianInEngland · Jan 31, 2023

bobkn said:
Sorry to be redundant. I was replying to a particular post, although my statements were general.

No problem

pparks1 · Jan 31, 2023

Dru2 said:
This is what I heard (read) you say...

In none of the boards you mention is this true - you STILL will have x16 speeds depending on what slots you use. And since each board you mentioned has MORE than one M.2 slot, you are NOT relegated to only getting x8 speeds.

Peace

On this MSI GodLike board, while it has 7 M.2 slots available, only 1 of the M.2 slots can do PCI Gen 5, and that's slot #4 as shown in the manual.

End of the day, i don't think nearly anyone is going to really be impacted in a negative fashion with one of these devices limited. But I wouldn't want to spend high-end money on a board, and a PCI Gen 5 video card, and a PCI Gen 5 NVMe only to find out that you cannot run them all at full speed. With that said, highly doubt for the forseeable future that any vide card in a pci-e gen 5 slot running at x8 is going to honestly be limited. Also, don't think unless you have 2 NVMe PCI-E Gen 5 drives in the same box and are copying from 1 to the other, that you are truly going to remotely come close to enjoying the possible speeds they can provide. And since the board can only support 1 M.2 slot at PCI-E Gen 5, you aren't going to be running 2 anyway.

BrianInEngland · Jan 31, 2023

pparks1 said:
On this MSI GodLike board, while it has 7 M.2 slots available, only 1 of the M.2 slots can do PCI Gen 5, and that's slot #4 as shown in the manual.View attachment 51448

End of the day, i don't think nearly anyone is going to really be impacted in a negative fashion with one of these devices limited. But I wouldn't want to spend high-end money on a board, and a PCI Gen 5 video card, and a PCI Gen 5 NVMe only to find out that you cannot run them all at full speed. With that said, highly doubt for the forseeable future that any vide card in a pci-e gen 5 slot running at x8 is going to honestly be limited. Also, don't think unless you have 2 NVMe PCI-E Gen 5 drives in the same box and are copying from 1 to the other, that you are truly going to remotely come close to enjoying the possible speeds they can provide. And since the board can only support 1 M.2 slot at PCI-E Gen 5, you aren't going to be running 2 anyway.

Absolutely agree, then there's the possibility of someone buying a 2-3K custom build, finding out that their £1500 4090 is only running at x8. Is the card faulty? Is the board faulty? They'll want answers from the builder/retailer.

I'm just surprised the limitation is there, the way Intel promote their newest high-spec kit!

hdmi · Jan 31, 2023

bobkn said:
With an M.2 card in M.2_1 (the CPU driven one), CPU-Z indicates that the graphics slot is limited to X8.

The link speed is shown as 2.5GT/s at idle. The little Render test in GPU-Z takes it up to the max, 16GT/s. That was true when the graphics slot was limited to X8, and it's still true at X16.

So even though GPU-Z says it's limited to x8, the actual bandwidth that you're getting is not limited (with 3DMark's PCIe bandwidth benchmark as proof), then IMO this confirms that the "x8" that is being reported by GPU-Z is referring to PCIe Gen 5 x8 which is equivalent to PCIe Gen 4 x16, @x16, just like I previously explained. (Remember that PCIe is BOTH backward AND forward compatible.)

bobkn said:
I don't recall whether I ever did an X8/X16 graphics comparison. Some online reviews showed a slight difference with my graphics card. (A few percent in gaming, variable depending on the game.)

Yeah, back in the old days it made less than 5% difference on average with a whole plethora of the most popular of GPU demanding games, as far as the fps scores were concerned. But with RTX 30xx cards AFAIK this difference in present day gaming tends to be significantly more noticeable. As you probably already know, for fast paced action games you really NEED that minimum fps counter to not start to dip on you or else you'll just get a big judder fest that causes the whole thing to become literally unplayable. But, that quad size 4090 Ti that got leaked the other day is a 800 watts electric popcorn maker.

bobkn · Jan 31, 2023

As far as I know, no graphics cards currentl`

bobkn · Jan 31, 2023

hdmi said:
So even though GPU-Z says it's limited to x8, the actual bandwidth that you're getting is not limited (with 3DMark's PCIe bandwidth benchmark as proof), then IMO this confirms that the "x8" that is being reported by GPU-Z is referring to PCIe Gen 5 x8 which is equivalent to PCIe Gen 4 x16, @x16, just like I previously explained. (Remember that PCIe is BOTH backward AND forward compatible.)

As far as I know, this is fantasy.

I presume that if a Gen4 graphics card (which the flagship AMD and nVidia cards still are) could operate at Gen5 X8, there would be much rejoicing. Many enthusiasts have been peeved to find their $1k+ cards being limited to X8 when an M.2 drive was used in the CPU's M.2 slot of their $1k gaming motherboards.

I might be able to test this without swapping around M.2 cards. I believe the MB BIOS will permit me to set the graphics slot to X8.

The PC is being rebuilt at the moment, so it'd be a few days.

BrianInEngland · Feb 1, 2023

What we all need is a decent consumer-level HEDT platform. I had an Intel X79 board, it was brilliant. Quad-channel RAM, 40+ PCI-E lanes from the CPU on a 2011-pin socket. Cost around £1k at the time for the whole kit (board, CPU, RAM).
My upgrade from that was originally an Asus X99 board, which was truly awful. Crashes, failed to boot with Fast boot enabled. Got rid of it after two weeks and went with the first AMD TR board, X399. It was new tech back then so had some problems but it worked. Again Quad-channel, loads of PCI lanes. Marketed to gamers (it was the Aorus Gaming 7 board).
Never bothered with X299 as I'd heard the cooling requirements were ridiculous

Been on AM4 since then, looking to go to AM5 soon. I say bring back a 2000-pin socket and give us 40 PCI lanes/quad RAM again!