This article covers 【限定】ASUS Intel CPU Core Ultra Processors (Series 2) LGA1851 対応 B860 Chipset mATX マザーボード.

Overview

ASUS PRIME B860M-A-CSM is a microATX motherboard based on the Intel B860 chipset, designed for Intel Core Ultra (Series 2) processors with the LGA1851 socket. This online retailers exclusive model omits onboard Wi-Fi to keep costs down, targeting users with stable wired network environments. It strikes a practical balance between features and price, making it a solid pick for mid-range builds.
The board supports up to 256GB of DDR5 RAM across four DIMM slots, with overclocking headroom beyond 8666MT/s. It includes a single PCIe 5.0 x16 slot for the latest graphics cards, plus two M.2 slots (one PCIe 5.0, one PCIe 4.0) and four SATA 6Gb/s ports for flexible storage. The power delivery system uses a 7+1+1+1 phase VRM rated at 80A per stage, providing ample stability for Core Ultra 7 and even Core Ultra 9 processors under typical loads.

Compatibility Guide

Socket compatibility is strictly LGA1851, meaning only Intel Core Ultra (Series 2, Arrow Lake) CPUs are supported. Older LGA1700 or LGA1200 processors are not compatible. Memory requires DDR5 DIMMs; DDR4 is not supported. The board supports AEMP III for automatic tuning of CUDIMM modules, and you can install up to 256GB across four slots.
With a microATX form factor (24.4cm x 24.4cm), it fits in most mATX and ATX PC cases. The single PCIe 5.0 x16 slot limits expansion to one GPU or add-in card; there are no additional PCIe slots. For storage, you get two M.2 slots (one Gen5 x4, one Gen4 x4) and four SATA 6Gb/s connectors. This setup works well for a primary NVMe SSD plus a secondary SSD or HDD.

Product Info

The ASUS PRIME B860M-A-CSM launched in late 2024 as online retailers exclusive. Pricing hovers around ¥19,700 (approx. $130 USD), positioning it as an affordable B860 option. It comes with standard ASUS warranty through the official Japanese distributor, typically three years.
Key features include the Intel B860 chipset (without overclocking support for K-series CPUs), Realtek 2.5Gb Ethernet, and a robust VRM setup. The board lacks discrete Wi-Fi/Bluetooth, so you'll need a wired connection or a USB adapter. BIOS Flashback is not confirmed, but ASUS typically includes it on this tier. The motherboard supports PCIe 5.0 for the primary GPU and one M.2 slot, ensuring future-proofing for high-speed components.

Best Use Cases

Budget-Mid Gaming Builds — If you're pairing a Core Ultra 5 or Ultra 7 with an RTX 4070-class GPU, this board provides PCIe 5.0 for the graphics card and a Gen5 M.2 for the OS drive without overspending on a Z890 chipset. Perfect for 1440p gaming rigs.
Office/Productivity PCs — For stable wired-office environments, the lack of Wi-Fi is a non-issue. You get reliable 2.5Gb Ethernet, plenty of SATA ports for HDD/SSD storage, and enough memory capacity for heavy multitasking or virtual machines.
Not Recommended For: Users who need multiple PCIe expansion slots (e.g., capture cards, RAID controllers), or those who must have built-in Wi-Fi and Bluetooth. Also, builders wanting maximum overclocking headroom should step up to a Z890 board.

Things to Consider

PCIe expansion is very limited — only one x16 slot and no additional x1 or x4 slots. If you plan to add a second GPU, a network card, or any PCIe-based accessory, this board won't accommodate them.
M.2 slot count is two, which may be insufficient for users wanting multiple high-speed NVMe drives. However, the four SATA ports partially mitigate this by allowing traditional SSDs or HDDs.
Because this is online retailers-exclusive SKU, you cannot purchase it from other retailers. Be sure to buy from an authorized online retailers seller to maintain warranty coverage. There's also no official information on Wi-Fi module installation options, so consider a USB Wi-Fi adapter if you ever need wireless connectivity.

FAQ

Q: Can I use a Core Ultra 9 285K with this motherboard?
A: Yes, the LGA1851 socket supports Core Ultra 9. The 7+1+1+1 phase VRM with 80A stages can handle sustained loads, but for heavy all-core overclocked scenarios, a board with more phases may be preferable.
Q: Does this board support Windows 11?
A: Yes. Core Ultra processors come with built-in TPM 2.0, and the motherboard firmware supports UEFI Secure Boot. No extra configuration is needed.
Q: Is there BIOS Flashback for CPU-less BIOS updates?
A: ASUS typically does not include USB BIOS Flashback on the PRIME B860M-A-CSM. You will need a compatible CPU installed to update the BIOS. Check the official support page for the latest version before building.

Product Disclosure (Amazon)

  • Manufacturer: ASUS
  • Seller: Amazon.co.jp
  • Fulfilled by: Amazon.co.jp
  • ASIN: B0DPMQJ2W7
  • Note: This article covers a manufacturer-made product based on Amazon listing details.