Part nvme pcie 4.0
- Thread starter Rmorrison
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PCI Express always was and likely will be compatible in both ways: you can put any version in any slot. Like, a PCI Express 4.0 NVMe drive works in a 2.0 slot (forward compatibility); a PCI Express 1.0 card works in a 4.0 slot (backwards compatibility).
Also note the 5.0 standard is already out (because 4.0 was very late) https://www.extremetech.com/computi...ow-available-before-pcie-4-0-has-even-shipped
Also note the 5.0 standard is already out (because 4.0 was very late) https://www.extremetech.com/computi...ow-available-before-pcie-4-0-has-even-shipped
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PCI Express is a type of connection and what it's used for is up to you: storage like M.2 NVMe drives, graphics cards, USB or SATA adapters, etc.
To be clear, NVMe is a protocol for storage devices (for PCIe storage only), like AHCI is for SATA storage only).
To be clear, NVMe is a protocol for storage devices (for PCIe storage only), like AHCI is for SATA storage only).
Mind you that while the standard (specifications) has been finished, there are no products yet. PCIe 4.0 had its specifications finished in June 2017, so two years ago. It is expected that PCIe 5.0 is going to be used for enterprise first (like PCIe 4.0 was) and it might enter consumer space in 2021 or 2022.
Yes: PCI Express is a bus and there are many physical interfaces utilizing it. On the desktop you will see PCI Express slots and various M.2 slots. Laptops use M.2 too and also Thunderbolt 3 which carries PCI Express and DisplayPort signal. Older laptops had ExpressCards and Mini PCI Express slots. Servers use U.2 and OCuLink. There are more obscure formats, but these are the physical formats most people will ever meet.
There is a lot of PCI Express between AMD server chips as well, as this article notes, "When I discuss the AMD EPYC 7001 series Infinity Fabric link between sockets, I usually tell people to conceptually think of it as a PCIe Gen3 x16 link between dies plus a little bit of extra juice. That is not entirely accurate, but most acquiesce that it is a decent rough conceptualization. "
As for NVMe, it's a "logical device interface specification for accessing non-volatile storage media attached via a PCI Express (PCIe) bus". Most common devices accessible via NVMe are M.2 key M SSDs (and some U.2 SSDs). Interestingly enough somewhat recently we have seen USB - to - M.2 enclosures which implement NVMe, it's interesting because generic USB - to - PCI Express is (almost) impossible because an USB client can't issue DMA requests and most PCI Express cards are DMA masters. While in theory it's possible to bridge this, the complexity and cost of it would probably be high enough it'd be cheaper to just swap the host computer for a Thunderbolt compatible one and then what's the point
? All Apple laptops are Thunderbolt compatible for a long while now and there are extremely few non cookie cutter PC laptops left in the world which are unique enough they can't just be exchanged with another for some reason (of course I have two but even one of those is TB3 compatible) so the market is super limited for a super expensive PCI Express enclosure-over-USB C-but-not-Thunderbolt 3.
There is a lot of PCI Express between AMD server chips as well, as this article notes, "When I discuss the AMD EPYC 7001 series Infinity Fabric link between sockets, I usually tell people to conceptually think of it as a PCIe Gen3 x16 link between dies plus a little bit of extra juice. That is not entirely accurate, but most acquiesce that it is a decent rough conceptualization. "
As for NVMe, it's a "logical device interface specification for accessing non-volatile storage media attached via a PCI Express (PCIe) bus". Most common devices accessible via NVMe are M.2 key M SSDs (and some U.2 SSDs). Interestingly enough somewhat recently we have seen USB - to - M.2 enclosures which implement NVMe, it's interesting because generic USB - to - PCI Express is (almost) impossible because an USB client can't issue DMA requests and most PCI Express cards are DMA masters. While in theory it's possible to bridge this, the complexity and cost of it would probably be high enough it'd be cheaper to just swap the host computer for a Thunderbolt compatible one and then what's the point
? All Apple laptops are Thunderbolt compatible for a long while now and there are extremely few non cookie cutter PC laptops left in the world which are unique enough they can't just be exchanged with another for some reason (of course I have two but even one of those is TB3 compatible) so the market is super limited for a super expensive PCI Express enclosure-over-USB C-but-not-Thunderbolt 3.
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