M.2 ?

R

ralphie1313

Limp Gawd
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Jan 15, 2019
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If someone can read the bottom of the picture were it says if M.2 _3 is enabled, PCIEX16_1 will run at x8 and PCIEX16_2 will run x4. So sorry i am not to good with computers but is this saying if i put an m.2ssd into slot 3 then my Pciex will run slower? and if so why ? What does that slot have to do with the PCIEX slots?

Thanks
 
what pic?
yes
not enough pcie lanes
they have to share lanes.
with your 4090 you may loose a few fps but you prob wont notice unless chasing high scores in benchmarks...
 
Hard to give you better advice when we don't know what picture you're looking at or even what motherboard you're using.
 
kirbyrj said:
Hard to give you better advice when we don't know what picture you're looking at or even what motherboard you're using.
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i assumed its his sig rig that we've been helping troubleshoot for the last week or so. still dont see a pic though...
 
Maybe he hasn't learned how to properly post pics yet. He clearly stated he's relatively new to PC's and is still figuring out how this all works and given time and some patience he'll get it. Ralphie I would be happy to help you if you'd like we can take this to private messaging for assistance so we don't clutter this thread unnecessarily.
 
A lot of the Asus boards have a gen 5 slot, so if you use that one it will kick your graphics card down to x8. Solution: use one of the 17 other slots on the board.
 
ralphie1313 said:
and if so why ? What does that slot have to do with the PCIEX slots?
Click to expand...

It runs on PCI Express lanes. Your computer has a fixed number of PCI Express lanes available to it, so if you use some for the M.2 drive, those lanes can no longer be used for PCI Express slots.

Some computers have PCI Express lanes that can be switched between different slots, including yours. If you put something on one type of slot, the other type of slot can't run at full speed or with full lane support.

It's like flushing a toilet while you're taking a shower. The water pressure in the shower drops because there's only so much water in the system, and when you divert a bunch of water to the toilet tank, the shower pressure drops.
 
kirbyrj said:
Hard to give you better advice when we don't know what picture you're looking at or even what motherboard you're using.
Click to expand...
sorry it did not upload, also i do have in my signature the mother board i am using it says asus x670-e
 

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Looks like pcie x16 1 and 2, and m.2 1,2, and 3 are most likely connected to CPU lanes, you've got 28 cpu lanes; 4 go to the chipset, 4 go to m.2-1, 4 go to m.2-2, and 16 are divided over the two pci-e x16 slots and m.2-3. From the table, If you use either of pci-e x16-2 or m.2-3, pci-e x16-1 only gets 8 lanes. But note that pci-e x16-3 and m.2-4 are connected through the chipsets, everything connected to the chipset is multiplexed to the cpu over the 4 lanes from the cpu to the chipset (and those are pci-e 4.0 lanes too, if that matters); x670 has a second chipset downstream of the first chipset, which gives you more I/O but no extra lanes to the cpu for it.

Luckily, few people are really maxing out throughput on their lanes, or it's very brief when it happens.
 
toast0 said:
Looks like pcie x16 1 and 2, and m.2 1,2, and 3 are most likely connected to CPU lanes, you've got 28 cpu lanes; 4 go to the chipset, 4 go to m.2-1, 4 go to m.2-2, and 16 are divided over the two pci-e x16 slots and m.2-3. From the table, If you use either of pci-e x16-2 or m.2-3, pci-e x16-1 only gets 8 lanes. But note that pci-e x16-3 and m.2-4 are connected through the chipsets, everything connected to the chipset is multiplexed to the cpu over the 4 lanes from the cpu to the chipset (and those are pci-e 4.0 lanes too, if that matters); x670 has a second chipset downstream of the first chipset, which gives you more I/O but no extra lanes to the cpu for it.

Luckily, few people are really maxing out throughput on their lanes, or it's very brief when it happens.
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So best one to use is the m.2_1 ?
 
Axman said:
It runs on PCI Express lanes. Your computer has a fixed number of PCI Express lanes available to it, so if you use some for the M.2 drive, those lanes can no longer be used for PCI Express slots.

Some computers have PCI Express lanes that can be switched between different slots, including yours. If you put something on one type of slot, the other type of slot can't run at full speed or with full lane support.

It's like flushing a toilet while you're taking a shower. The water pressure in the shower drops because there's only so much water in the system, and when you divert a bunch of water to the toilet tank, the shower pressure drops.
Click to expand...
so i got my m.2 in slot one and the gpu of course in pci 1 slot is that effecting anything if so what should i do am i better of with a scsi ssd?
 
m.2 in slot 1 and GPU in PCIe 1 is the right answer.

The second part of the right answer is don't worry about it. If you have to add more m.2 drives just stick them into a slot. Even if you were to pick a slot that is bandwidth shared, it's highly unlikely that you are running anything where you'd actually notice the difference. A bandwidth shared NVMe (m.2) drive is still faster than, or at least as fast as, a SATA drive.
 
pitingres said:
m.2 in slot 1 and GPU in PCIe 1 is the right answer.

The second part of the right answer is don't worry about it. If you have to add more m.2 drives just stick them into a slot. Even if you were to pick a slot that is bandwidth shared, it's highly unlikely that you are running anything where you'd actually notice the difference. A bandwidth shared NVMe (m.2) drive is still faster than, or at least as fast as, a SATA drive.
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i gotcha !! thanks
 
Axman said:
It runs on PCI Express lanes. Your computer has a fixed number of PCI Express lanes available to it, so if you use some for the M.2 drive, those lanes can no longer be used for PCI Express slots.

Some computers have PCI Express lanes that can be switched between different slots, including yours. If you put something on one type of slot, the other type of slot can't run at full speed or with full lane support.

It's like flushing a toilet while you're taking a shower. The water pressure in the shower drops because there's only so much water in the system, and when you divert a bunch of water to the toilet tank, the shower pressure drops.
Click to expand...
Bingo.

When I run a second NVME M2 I lose my second PCIE slot altogether.
 
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