Performance and PCI Express Bus Lanes
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Date: Tue, 07/28/2020 - 18:02
The amount of PCI Express lanes you have available to you through your PC, largely depends on your CPU and your Chipset. With Intel’s modern chipsets, your CPU largely determines how many PCI lanes you have available to you through your PC.
SKIP TO: Chipset, CPU, and Performance
Why Do PCI-Express Lanes Matter?
Your PCI Express 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 those functions that have to do with your primary PCIe slots.
Typical Functions Your CPU's PCIe Lanes Control:
- CPU Processing
- Onboard Video
- PCIe 3.0 x16 Slot (more on some boards)
- M.2/U.2 (on some Enthusiast Boards)
- LAN (on some Enthusiast Boards)
Other functions use your CHIPSET's PCIe bus lanes. Older chipsets designate less PCIe 2.0/3.0 lanes for these functions. Functions which your chipset's PCIe lanes control may include:
- SATA hard drives
- Onboard Sound
- Onboard RAID
- Onboard Network Controller
- PCIe cards plugged into your PCIe x1 slot
- All PCIe slots except the first one (Socket 1150/1151)
- Onboard LAN
- Onboard Sound
- Sound card
- Network card
- RAID controller card
The following are generally accepted amounts of PCIe bandwidth which various components require:
- 8-16 Lanes - x16 PCIe Video Cards (Each)
- 8-16 Lanes - FPGA & Other Specialized PCIe Cards
- 4 Lanes - M.2 Drive
- 4 Lanes - Thunderbolt (uses 4 lanes PCIe 3.0)
- 4 Lanes - Hardware Based RAID Controllers
- 2 Lanes - Output For One 4K Video Display
- 2 Lanes (Each) - SSD Drives
- 2 Lanes - USB 3.1 (Gen. 2)
- 1 Lane - USB 3.0 (USB 3.1 Gen. 1)
- 1 Lane - Sound
- 1 Lane - Network Controllers
Performance PC 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 16 lanes of PCIe bus.
However, if you are planning to use your PC for applications that may add up to more than 16 lanes of bus bandwidth, then using Chipsets and CPUs with less PCIe lanes may become a bottleneck for your system, especially during times of intense usage.
PCIe 3.0 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 3.0). PCIe 3.0 has almost doubled the effective bandwidth (after overhead) of each PCIe bus lane when compared to PCIe 2.0. PCIe 2 had 500 MB/s effective bandwidth. PCIe 3.0 has 985 MB/s effective bandwidth. Upcoming platforms, including 3rd Generation Ryzen and Threadripper PCs, will use PCIe 4.0, which has 1.969 GB/s bandwidth per bus lane.
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?
Intel's X-Series CPUs (Skylake-X) are Intel’s performance line of CPUs. Overall, these CPUs have more performance potential than Socket 1200 CPUs (Intel's 8th Generation Core Consumer CPUs). However, X-Series CPUs (Socket 2066 i9) are more expensive and produce more heat (use more power and require more cooling through the use of larger heatsinks and fans). The upper end of 3rd generation AMD Ryzen outperforms even Intel's X-Series CPUs, but high end CPUs require large heatsinks with fans to cool them, just like Skylake-X, and thus high-end Ryzen CPUs aren't available in fanless systems. 3rd generation AMD Ryzen Threadripper outperforms them all, with truly outstanding CPU performance benchmarks.
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 performers here.
The following chart explains the performance, bus lanes, and power usage of various chipsets featured in our PCs, to help you make your decision about which PC is right for you. In our chart, we used Passmark CPUMark rankings from this resource (as of the time of this writing), for your convenience. If you wish to look up your particular CPU's performance please refer to: https://www.cpubenchmark.net/cpu_list.php
|Chipset||Chipset Lanes||Socket||CPU||CPU Lanes||CPU Benchmarks||CPU Heat|
|Intel H310||6 PCIe 3.0 Chipset Lanes||Socket 1151||Coffee Lake i5-8500T to i7-8700T||16 PCIe 3.0 CPU Lanes||8228 to 10176||35w|
|Intel C242||10 PCIe 3.0 Chipset Lanes||Socket 1151||Xeon Entry E-2134 to E-2136||16 PCIe 3.0 CPU Lanes||10909 to 15914||71w to 80w|
|Intel B460||16 PCIe 3.0 Chipset Lanes||Socket 1200||Comet Lake i3-10100 to i7-10700K||16 PCIe 3.0 CPU Lanes||8050 to 19795||51w to 91w|
|Intel H470||20 PCIe 3.0 Lanes||Socket 1200||Comet Lake i3-10100 to i7-10700K||16 PCIe 3.0 Lanes||8050 to 19795||65w to 95w|
|Intel Z490||24 PCIe 3.0 Lanes||Socket 1200||Comet Lake i3-10100 to i7-10700K||16 PCIe 3.0 Lanes||8050 to 19795||54w to 95w|
|AMD X570||12 PCIe 4.0 Lanes||Socket AM4||Ryzen 5 3400G to Ryzen 9 3950X||24 PCIe 4.0 Lanes
(4 Used To Interface with Chipset)
|9996 to 36015||65w to 95w|
|AMD X399||64 PCIe 3.0 Chipset Lanes Total||AMD TR4||Threadripper 1900X to 2990WX||NA||15401 to 24049||180w to 250w|
|AMD TRX40||88 PCIe 4.0 Chipset Lanes Total||AMD sTRX4||Threadripper 3960X to 3990X||NA||55692 to 80492||280w|
|Intel X299||24 PCIe 3.0 Chipset Lanes||Socket 2066||Skylake-X i9-10900X to i9-10980XE||48 PCIe 3.0 CPU Lanes||24159 to 29576||165w|
|Intel C422||24 PCIe 3.0 Chipset Lanes||Socket 2066||Xeon-W Workstation CPUs W-2123 to W-2195||48 PCIe 3.0 CPU Lanes||9375 to 27795||120w to 140w|
|Intel C621||20 PCIe 3.0 Chipset Lanes||Socket 3647||Dual Xeon Bronze 3104 to Dual Xeon Platinum 8153
3rd Gen Xeon-W CPUs W-3223 to W-3265
|48 PCIe 3.0 CPU Lanes Each CPU||9410 to 35948 (Gold 6154)
24445 to 31691
|125w-205w Each CPU
180w to 205w