B850 is AMD's mainstream AM5 chipset and the one most new Ryzen builds should start from. It arrived in early 2025 as the successor to B650. Every B850 board allows CPU and memory overclocking and has at least one PCIe 5.0 M.2 slot. A PCIe 5.0 graphics slot and USB4 are optional, so they vary by board. You can compare current prices on the B850 deals page.
Cheapest B850 boards right now
All 126 B850 motherboards, with price drops and price history
Amazon Warehouse offers on B850 boards
Where B850 sits
The 800-series for AM5 runs X870E, X870, B850, then B840. B850 is the lowest tier that still overclocks the CPU. Like X870 it uses a single chipset chip, and it is a refresh of B650 rather than a new design: the main change is that a PCIe 5.0 M.2 slot went from optional to compulsory.
The chipset does not affect how fast your processor runs. A Ryzen 7 on a B850 board performs the same as on X870E, so long as the board's power delivery suits the chip.
Key specifications
| Feature | X870 | B850 | B650 |
|---|---|---|---|
| Launched | 2024 | Early 2025 | 2022 |
| CPU overclocking | Yes | Yes | Yes |
| PCIe 5.0 graphics slot | Required | Optional, varies by board | Not guaranteed |
| PCIe 5.0 M.2 slot | Required | Required | Optional, varies by board |
| USB4 | Required | Optional, varies by board | Optional, on few boards |
| Memory | DDR5 | DDR5 | DDR5 |
The PCIe 5.0 lanes come from the processor. The chipset's own lanes are PCIe 4.0. That is the practical difference from B840 below it, where the chipset provides only PCIe 3.0 and CPU overclocking is removed.
Compatible CPUs and memory
B850 supports Ryzen 7000, Ryzen 8000G and Ryzen 9000 processors. Ryzen 9000 works from the first BIOS. If you buy a chip that was released after your board was made, check the board's CPU support list for the BIOS version it needs; our BIOS guide explains how to update without a working CPU.
Memory is DDR5 only, with EXPO and XMP profiles. There is no DDR4 option on AM5. AMD has said AM5 is supported through 2027 and beyond, so the socket is not yet at the end of its life.
Ryzen 8000G processors are PCIe 4.0 parts and have fewer lanes than the other AM5 chips. With one fitted, PCIe 5.0 slots run at 4.0 speed, and on some boards a secondary M.2 slot runs slower or is disabled. The board manual lists this.
B850 against its neighbours
Against X870: the two differ mainly in USB4 and guaranteed PCIe 5.0 graphics. If you want either, check whether a particular B850 board has it before paying more for X870. If you want neither, B850 gives away nothing. See X870E vs X870 vs B850.
Against B650: the chipsets are closely related. B850 boards are newer, all have a PCIe 5.0 M.2 slot, and start Ryzen 9000 chips without a BIOS update. B650 boards are older stock, which is where reductions tend to appear. For most builds the cheaper of two similarly equipped boards is the right choice; B850 vs B650 goes through it.
What varies by board
- Graphics slot speed. Some B850 boards wire the main slot for PCIe 5.0 and some for PCIe 4.0. Current graphics cards lose nothing noticeable at PCIe 4.0 x16.
- M.2 slots. One PCIe 5.0 slot is guaranteed. The number and speed of the others is up to the maker.
- Power delivery. B850 spans budget boards and ones built as well as X870 models. For a 12- or 16-core chip, read VRMs explained first.
- WiFi, Ethernet speed and audio. All board features. Many models are sold in WIFI and non-WIFI versions.
- Size. B850 is sold in ATX, micro-ATX and mini-ITX.
Who should buy B850
B850 fits a gaming or general-purpose PC with one graphics card and one to three SSDs, which describes most builds. You keep overclocking and Precision Boost tuning, you get a fast slot for the main SSD, and you avoid paying for ports you will not use. Step up to X870 for USB4, or to X870E if you need many drives and add-in cards at once. Step down to B840 or A620 only if you are sure you will never overclock and the saving is real.
What to check on the listing
- Whether the main graphics slot is PCIe 5.0 or 4.0, if that matters to you.
- The count and speed of M.2 slots.
- WIFI or non-WIFI version, and the WiFi generation.
- Rear USB ports, including any USB-C.
- Whether there is a BIOS flashback button.
- For Warehouse offers, the condition note. AM5 pins sit in the board's socket, so inspect it on arrival using our used motherboard checklist.
The B850 deals list shows each board's current price against its own history, with Warehouse offers listed separately.
Questions people ask
Does B850 support PCIe 5.0?
Every B850 board has at least one PCIe 5.0 M.2 slot. A PCIe 5.0 graphics slot is optional: some B850 boards have one and others run the graphics slot at PCIe 4.0, so check the listing.
Can you overclock on B850?
Yes. B850 allows both CPU and memory overclocking. B840 and A620 below it allow memory overclocking only.
Is B850 better than B650?
It is newer and guarantees a PCIe 5.0 M.2 slot, which B650 does not. The two chipsets are otherwise closely related, and processor performance is the same. A B650 board may need a BIOS update before it will start a Ryzen 9000 chip.
Do B850 motherboards have USB4?
Some do, but it is not required. USB4 is compulsory only on X870 and X870E. Check the rear port list for the board you are looking at.