Last summer, it was reported the PCI-SIG consortium is working on PCI Express 8.0 technology to succeed PCI Express 6.0 and 7.0 and deliver transfer speeds eight times higher than today’s PCI Express 5.0. Deployment is still a long way off, but work on the draft has now advanced to version 0.5. PCIe 8.0 could prove to be a major turning point in PC development, because it may involve changes to connectors and slots.
As reported last August, PCI Express 8.0 will raise single-lane speed to 32 GB/s—something difficult to imagine today, considering that for example an entire PCIe 5.0 ×4 SSD interface currently delivers 16 GB/s across four lanes. However, each generation (6.0, 7.0, and 8.0) will double speed, causing rapid cumulative growth.
An M.2 slot for SSDs with four lanes would therefore provide 128 GB/s of bandwidth (in both directions simultaneously, for reading and writing), while a PCIe 8.0 ×16 slot for GPUs would reach 512 GB/s. PCI-SIG often cites combined bidirectional bandwidth, and by that calculation PCIe 8.0 ×16 would provide 1 TB/s.
PCI Express 8.0 still assumes backward compatibility will be preserved, meaning older devices will be able to communicate with newer ones and vice versa. Naturally, they will only operate at the highest speed supported by both devices (and by the motherboard between them). However, the increasing speeds are becoming progressively more difficult to implement over traditional copper traces due to growing sensitivity to interference, timing precision, signal reflections, and related issues.
PCI Express 8.0 could therefore involve changes to connectors—meaning the slots and/or the edge connectors on expansion cards, and M.2 modules. Or potentially even some entirely new connector type. That means while the electrical signaling itself may remain compatible, allowing a new PCIe 8.0 device to communicate with an older CPU supporting only PCIe 4.0 or 5.0, practical compatibility may still depend on whether the motherboard provides the appropriate new connector type.
In theory, this could create a situation where consumer motherboards include two connector types—one legacy type for compatibility with older peripherals and another distinct type for the newest GPUs, into which older cards won’t fit. That would significantly disrupt the way how desktop motherboards have functioned over the last two decades.
However, things may not go that far. The possibility of altered connectors is currently something that’s still being evaluated and nothing in that direction has been decided. More importantly, connector changes do not necessarily have to break compatibility if they are only partial. For example, they could involve structural modifications designed to improve signal quality while still allowing older PCI Express cards to fit into new PCIe 8.0 slots—or conversely allowing new cards to be installed in older slots.
PCIe 8.0’s arrival in consumer PCs is still far away
The PCIe 8.0 specification is expected to be finalized in 2028. However, completion of the specification traditionally does not mean immediate practical deployment, which usually takes several more years. PCI Express 8.0 will likely first see adoption mainly in datacenters and similarly demanding (and expensive) hardware sectors. In consumer PCs and notebooks, it may take several additional years before the new interface version begins to appear. PCI Express 7.0 was completed last year, yet its practical deployment remains a matter for the future.
For example, PCI Express 6.0 devices and platforms are expected to gradually begin appearing in servers this year, but according to SSD and controller manufacturers, consumer PCs are unlikely to get PCIe 6.0 SSDs until around 2030. Until then, SSDs will be stuck using PCI Express 5.0 ×4, even though that interface’s speed ceiling has been already exhausted by current NVMe modules and speeds could actually scale further today if SSDs were given higher-bandwidth link to the CPU. The PCIe 6.0 standard itself was finalized back in 2022.
From this, it can be inferred that SSDs using PCIe 7.0 and later PCIe 8.0 will take proportionally longer still to arrive in laptops and gaming PCs.
Sources: techPowerUp, PCI-SIG
English translation and edit by Jozef Dudáš
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