PCIe Question

[IamNooob]

Hello, just put together a z790 Aorus with a 14700k build . I am going to stick with my 3080 until the new gen releases. I would like to pick up a bigger ssd which will run up to 4.0. I had to manually set the lane to 3.0 for my gpu so will I be able to run the new ssd at 4.0 or are all the lanes now 3.0? I know there are a few bios settings but I cannot find anything on this.  I know it's backward compatible but would prefer to utilize the 4.0 feature of the SSD.  

 

Cheers 

Aorus z790 Elie

14700k 

Asus Tuff RTX 3080

Corsair V 32gb 6400 

[MiszS]

Not sure, but why would you set the gpu to pcie 3?

[IamNooob]

It was required for the MB to post video. I went back and set it to 4.0 after the fact but was getting terrible fps drops until reverted back to 3 

[RONOTHAN##]

I think there's some misconceptions about how any of this works. PCIe gen is on a slot per slot basis, so changing the version of one slot would do nothing to the version of another. PCIe lane count can be affected (I.E. motherboards with x16/x0 or x8/x8 functionality), but that's not what's going on here. 

 

Why would setting the GPU to PCIe Gen 3 allow your SSD to run at Gen 4? One thing has nothing to do with the other. 

 

2 minutes ago, IamNooob said:

It was required for the MB to post video. I went back and set it to 4.0 after the fact but was getting terrible fps drops until reverted back to 3 

That sounds more like a hardware issue than anything. If you're running a PCIe riser, that would cause this, though if not I think you might've gotten a bad motherboard. 

[IamNooob]

Yes I am running a riser, I should have included that in the op. I just don't know if the m.2 is tied to the CPU/PCIe lane which is running @ 3.0 because of the riser. I believe the PCH/PCIe is on a separate chipset which is not intended for OS. Bottom line, if I throw in a new Samsung 990 will it run 3.0 or 4.0?  I will have to do some research so I can understand the distribution of bandwidth and how m.2 affects the bus. 

 

 

[adm0n]

16 minutes ago, IamNooob said:

Yes I am running a riser, I should have included that in the op. I just don't know if the m.2 is tied to the CPU/PCIe lane which is running @ 3.0 because of the riser. I believe the PCH/PCIe is on a separate chipset which is not intended for OS. Bottom line, if I throw in a new Samsung 990 will it run 3.0 or 4.0?  I will have to do some research so I can understand the distribution of bandwidth and how m.2 affects the bus. 

 

 

The way it looks from the picture, you actually only have control over all lanes of the CPU at once. If there are no other options, you might need to live with it.

 

But it doesn't really matter that much. Even if you're only getting PCIe 3.0 speeds for your SSD, you only rarely get into situations, where you need more than 3.5GB/s sequential writes. And SSDs only support writing that fast until their cache fills up anyway. Their random reads/writes performance (IOPS) is way more important, and the PCIe version doesn't effect it. So you can just buy which ever SSD you like!

[Mark Kaine]

i mean you're using a 3.0 riser, so you're going to have to live with 3.0 or stop using the riser i guess? also 3.0 vs 4.0 is more like a marketing gimmick,  sure its faster but rarely noticeable by humans in real life scenarios. 

[IamNooob]

Ok thanks for the input friends. Happy Holidays 

[Mark Kaine]

same to you!

[Mark Kaine]

9 hours ago, adm0n said:

The way it looks from the picture, you actually only have control over all lanes of the CPU at once. If there are no other options, you might need to live with it.

 

But it doesn't really matter that much. Even if you're only getting PCIe 3.0 speeds for your SSD, you only rarely get into situations, where you need more than 3.5GB/s sequential writes. And SSDs only support writing that fast until their cache fills up anyway. Their random reads/writes performance (IOPS) is way more important, and the PCIe version doesn't effect it. So you can just buy which ever SSD you like!

yeah i bought a "slow" pcie3 evo 980 nvme, and its so much faster than sata... anything faster shouldn't really be noticeable unless someone transfers *a lot* of data... 

[adm0n]

On 11/27/2023 at 6:16 PM, Mark Kaine said:

yeah i bought a "slow" pcie3 evo 980 nvme, and its so much faster than sata... anything faster shouldn't really be noticeable unless someone transfers *a lot* of data... 

You actually have a (measurably) slower drive. Since the 980 Evo doesn't have a DRAM Cache it has to rely on your computers RAM to store the index to your data. And you don't have the cache for reads/writes either. So it will have to go straight to NAND (which has become fast enough, that you likely won't notice the difference).

 

All in all it is a good drive! But there is more to SSDs than the way it interfaces with your PC.