Warning: Technology changes very quickly so it is always recommended that you look at the date when the article was last updated. If you have any questions feel free to contact us.

Article Date: 02-23-2023

PCI Express Bus Lanes

The amount of PCI Express bus lanes you have available to you through your PC depends on your CPU lanes, your Chipset lanes, and your Chipset DMI (Direct Media Interface) version. With modern enthusiast chipsets, your CPU largely determines how many PCI lanes you have available to you through your PC. With budget minded chipsets, your data often flows through the DMI (Direct Media Interface - Intel) or UMI/Uplink (AMD) to get the data from the chipset side of your motherboard.

Current Chipset PCIe Bus Lane/DMI Chart

Why Do PCIe Lanes Matter?

Your PCI Express bus lanes consist of the lanes of communication that your motherboard uses to control your PC's functions. Your CPU, in particular, controls your CPU and memory, as well as typically controlling your first PCIe slot and usually your first PCIe slot and usually your first NVMe M.2 drive.

Typical Functions Your CPU's PCIe Lanes Control:

Other functions use your CHIPSET's PCIe bus lanes. Older chipsets designate less PCIe 2.0/3.0/4.0 lanes for these functions. Functions which your chipset's PCIe lanes control may include:

The following are generally accepted amounts of PCIe 4.0 bandwidth which various components require:

PCIe Bandwidth Demands

The number of PCIe bus lanes you have available to you can determine the performance of your PC, particularly if you are using performance sensitive software, such as Photo/Video Software, CAD, Financial Software, Audio Production Software, etc. Additionally, if you use your PC for intensive gaming application or to support multiple high-definition monitors, you will have an increased demand placed on your PCIe bus lanes.

If you aren't using your PC for performance demanding applications, it isn't likely you need more than 12 lanes of PCIe bus. You might only use a computer for browsing, media, or as a simple kiosk, then you would do fine choosing a chipset with less lanes. However, if you are planning to use your PC for demanding applications or using multiple high speed M.2 drives then using Chipsets and CPUs with less PCIe lanes may become a bottleneck for your system, especially during times of intense usage.

PCIe 4.0 Effective Speed

When all PCIe bus lanes are being used on a PC, your PC negotiates which device gets how much PCIe bandwidth. Most of the motherboards we use in our systems use the latest version of PCIe (PCIe 4.0). PCIe 4.0 has almost doubled the effective bandwidth (after overhead) of each PCIe bus lane when compared to PCIe 3.0.

If you are using your PC for demanding applications, it is recommended that you choose a system with more available PCIe lanes.

Which Chipset Should I Use?

The Intel Z790 Chipset is Intel's highest performing consumer oriented chipset. Intel's latest 13th/12th generation CPU have more performance potential than previous generations. The upper end of AMD Ryzen 7000 series CPUs slightly outperform Intel CPUs. For a true performance PC without needing to jump to a server motherboard, we recommend an AMD Threadripper.

In the workstation/server platforms (designed for stability), we offer three Intel platforms: Intel Xeon Entry, Intel Xeon-W, and Intel Scalable. We offer one AMD platform: AMD EPYC. AMD and Intel both offer good performance. As always you can speak to us regarding any questions you have about your particular computer needs. Sending us an email is the best way to get your questions researched and answered throughly. Technical Support - support@silentpc.com

What Is DMI (Direct Media Interface)

DMI is Intel's name for the lanes through which data moves from the storage and peripheral side fo the motherboard to the CPU side of the motherboard. UMI or Uplink is AMD's name for those lanes in between the CPU lanes and the Chipset lanes. The number of lanes on the DMI (Direct Media Interface) determine how fast and how much information can move from one side of the motherboard to the other. In enthusiast motherboards and most server motherboards, the DMI is less of a factor because the high speed storage devices live on the CPU side of the motherboard.

The following charts explain current CPU Bus Lanes, DMI Version, and Chipset Bus Lanes (as of this writing) to help you make your decision about which PC is right for you.


 
Chipset Chipset
PCIe 4.0 Lanes
Chipset
PCIe 3.0 Lanes
CPU/s Supported CPU
PCIe 4.0 Lanes
CPU Heat
Intel Z790 20 8 13th/12th Generation Intel Core - Raptor Lake/Alder Lake 20 DMI 4 x 8
~ PCIe 4.0 x8
Intel H770 16 8 13th/12th Generation Intel Core - Raptor Lake/Alder Lake 20 DMI 4 x 8
~ PCIe 4.0 x8
Intel B760 10 4 13th/12th Generation Intel Core - Raptor Lake/Alder Lake 20 DMI 4 x 4
~ PCIe 4.0 x4
Intel H610 0 12 12th Generation Intel Core - Alder Lake 20 DMI 4 x 4
~ PCIe 4.0 x4
Intel B560 0 12 11th Generation Intel Core - Rocket Lake 20 DMI 3 x 4
~ PCIe 3.0 x 4
Intel C252* 0 10 Xeon Entry E-2300 Server Processors - Rocket Lake 20 DMI 3 x 4
~ PCIe 3.0 x 4
Intel C621A 0 20 3rd Generation Xeon Scalable / Xeon W-3300 - Ice Lake 64 DMI 3 x 4
~ PCIe 3.0 x 4

*On C252/C621A motherboards M.2, RAM, and PCIe 4.0 slots are typically connected directly to the CPU/s

 

Chipset Chipset Lanes
(Up To 5.0)
CPU/s Supported CPU
PCIe 4.0 Lanes
UMI/Uplink
AMD B650 36 AMD Ryzen 7000 CPUs (Zen 4 CPUs) 24 DMI 4 x 4
AMD X670E 44 AMD Ryzen 7000 CPUs (Zen 4 CPUs) 24 DMI 4 x 4
AMD WRX80* 152 AMD Ryzen Threadripper PRO 128 DMI 4 x 8
System on Chip AMD EPYC 7002/3 Series 128

*On WRX80 motherboard M.2, RAM, and PCIe 4.0 slots are connected directly to the CPU's PCIe lanes

Related Systems


Some of our systems related to this article

Intel Raptor Lake Elite PC

Intel Raptor Lake Elite PC

  •   Intel 14th Generation up to 24 cores
  •   Max 192GB DDR5
  •    9.1in W x 20.9in D x 18.2in H
  •   Mid tower PC

Starting at $2,425.00

AMD Ryzen 7000 Elite PC

AMD Ryzen 7000 Elite PC

  •   AMD Ryzen 7000 up to 16 cores
  •   Max 64GB DDR5
  •    9.1in W x 20.9in D x 18.2in H
  •   Mid tower PC

Starting at $2,200.00

AMD Ryzen Threadripper PC

AMD Ryzen Threadripper PC

  •   AMD Threadripper 7000 up to 96 cores
  •   Max 384GB ECC DDR5
  •    9.4in W x 23.8in D x 22.3in H
  •   Full tower PC

Starting at $5,130.00

Quiet Xeon-W Workstation

Quiet Xeon-W Workstation

  •   Intel Xeon-WX up to 36 cores
  •   Max 512GB ECC DDR5
  •    9.4in W x 23.8in D x 22.3in H
  •   Full tower HEDT PC with ECC RAM
    10G Networking and PCIe 5.0

Starting at $5,720.00

Newsletter


Subscribe to our newsletter and get the latest on product releases and helpful tips and tricks.