Higher PCIe generations ensure that future GPUs won't be bottlenecked by the bus. While a Gen 3 x16 slot is mostly fine for an RTX 4090 today, that won't hold true for the GPUs of 2027.
At that speed, a x16 slot will push roughly . To put that in perspective: that is enough bandwidth to move the entire contents of a 1TB SSD in roughly two seconds. pcie specification
This layer handles the business logic of the bus. It assembles packets called . Higher PCIe generations ensure that future GPUs won't
As speeds increased, the 8b/10b encoding became too inefficient (losing 20% of raw bandwidth to overhead). To put that in perspective: that is enough
Progressing on Track: PCIe 7.0 Specification, Version 0.7 Now Available for Member Review. ... As we enter 2025, I am pleased to a... PCI-SIG https://pcisig.com PCI Express 6.0 Specification PCIe 6.0 Specification Features * 64.0 GT/s raw data rate and up to 256.0 GB/s via x16 configuration. * Pulse Amplitude Modulation... Wikipedia https://en.wikipedia.org PCI Express - Wikipedia Compared to earlier standards, PCIe supports faster data transfer, uses fewer pins, takes up less space, and allows devices to be ... Show all Generation Launch Year Raw Bit Rate (per lane) x16 Bandwidth (Bi-directional) Key Technologies PCIe 3.0 2010 8 GT/s 32 GB/s 128b/130b encoding PCIe 4.0 2017 16 GT/s 64 GB/s Doubled throughput for SSDs PCIe 5.0 2019 32 GT/s 128 GB/s Targets AI accelerators & 400G Ethernet PCIe 6.0 2022 64 GT/s 256 GB/s PAM4 signaling
Marketing loves bandwidth (GB/s). Engineers love latency (nanoseconds). The spec carefully defines latency budgets for things like NVMe over PCIe. A GPU might not need 128 GB/s of bandwidth for a simple draw call, but it cannot tolerate a 1-microsecond delay.