PCIe Lanes Limitations

Discussions center on the number of PCIe lanes provided by CPUs, their bandwidth capacities across versions like PCIe 3.0/4.0/5.0, and whether they create bottlenecks for GPUs, NVMe drives, NICs, and other peripherals, with comparisons between AMD and Intel processors.

➡️ Stable 0.5x Hardware
2,580
Comments
18
Years Active
5
Top Authors
#9481
Topic ID

Activity Over Time

2009
2
2010
4
2011
6
2012
9
2013
28
2014
26
2015
49
2016
91
2017
261
2018
116
2019
194
2020
214
2021
254
2022
324
2023
281
2024
399
2025
311
2026
11

Keywords

RAM e.g CPU PCH LRDIMM RAID GB X570 GPU OEM pcie lanes bandwidth nvme pci bottleneck 16 gpu nic queue

Sample Comments

Viper007Bond Oct 15, 2017 View on HN

PCIe lanes usually. CPUs only give you so many.

CyberDildonics Nov 25, 2023 View on HN

PCIe bandwidth is not typically a bottleneck, it has kept ahead of what people need. 8 lanes of PCIe is already 16 GB/s

virtuallynathan Jun 12, 2019 View on HN

I don't think it has more PCIe lanes -- those are limited by the IO die, afaik.

asdfs Jun 10, 2013 View on HN

Wouldn't you suffer from lower bandwidth than over PCIe, though?

Kubuxu Feb 26, 2017 View on HN

Usually you don't need x16 lanes for each GPU. x8 or even x4 in PCIe 3.0 will be enough but there is no way to know without checking.

shaklee3 Nov 23, 2022 View on HN

the problem is PCIe speeds are increasing faster than network. pcie5 can hit 500Gbps in theory, but the network is only 400Gbps.

Dylan16807 Dec 29, 2024 View on HN

How much PCIe bandwidth do you need to avoid it being the bottleneck?

gorkish Jun 5, 2023 View on HN

There's plenty of bandwidth despite the limited number of lanes; I'd think with a PCIe switch everything would be just fine...

AlphaSite Oct 5, 2017 View on HN

Go for an AMD chip, you get 60-128 general purpose Pcie lanes.

hajile Jul 13, 2017 View on HN

64 instead of 24 pcie lanes is huge too