ASRock B850M Pro RS VS Asus Prime B840M-A

At a high level, the ASRock B850M Pro RS and the Asus Prime B840M-A are remarkably alike. Both are Micro-ATX boards sharing an identical 244 × 244 mm footprint, both target the AM5 platform, support overclocking, feature dual BIOS, include RGB lighting, and carry a 3-year warranty. Neither board offers integrated Wi-Fi, Bluetooth, or an integrated GPU, so users on both platforms will need to budget for a discrete graphics card and, if needed, a wireless adapter.

The only meaningful differentiator within this spec group is Easy to reset BIOS: the Asus Prime B840M-A supports it, while the ASRock B850M Pro RS does not. In practice this matters most during failed overclocks or bad BIOS flashes — a dedicated clear-CMOS button or BIOS Flashback-style mechanism lets you recover the board without needing a working CPU or display. The ASRock's lack of this feature is not a dealbreaker for experienced builders, but it adds friction in recovery scenarios.

For this spec group, the Asus Prime B840M-A holds a narrow but practical edge purely because of its easier BIOS reset capability. Every other general characteristic is identical, so if painless recovery from a bad BIOS state matters to you — especially on a new AM5 build where firmware updates are still frequent — the Asus board has the more forgiving design.

Both the ASRock B850M Pro RS and Asus Prime B840M-A support a maximum memory amount of 256GB and feature 4 memory slots. They both also use DDR5 memory and operate with 2 memory channels. The key difference between these two models lies in their overclocked RAM speed. The ASRock B850M Pro RS supports an overclocked RAM speed of 8000 MHz, while the Asus Prime B840M-A supports a slightly lower overclocked RAM speed of 7600 MHz.

Neither motherboard supports ECC (Error-Correcting Code) memory, which means neither is optimized for error correction in critical applications. Despite this, both boards are capable of handling high-performance memory configurations.

Overall, the main distinction between the two is the ASRock B850M Pro RS's higher overclocked RAM speed, giving it a slight edge in memory performance in this regard.

The ASRock B850M Pro RS and Asus Prime B840M-A both offer a variety of USB ports, but there are some differences in their configurations. The ASRock B850M Pro RS has 1 USB 3.2 Gen 2 port (USB-A), 2 USB 3.2 Gen 1 ports (USB-A), and 1 USB 3.2 Gen 2 port (USB-C). The Asus Prime B840M-A, on the other hand, offers 2 USB 3.2 Gen 2 ports (USB-A) and 1 USB 3.2 Gen 1 port (USB-A), but it does not have any USB 3.2 Gen 2 ports (USB-C). Both boards have 4 USB 2.0 ports.

In terms of display outputs, the ASRock B850M Pro RS has 1 DisplayPort output and 1 HDMI output, while the Asus Prime B840M-A features 2 DisplayPort outputs along with its HDMI output. Both motherboards feature 1 RJ45 port, ensuring wired Ethernet connectivity. Additionally, both models support USB Type-C connectivity.

Neither motherboard has USB 3.2 Gen 2x2 ports, USB 4 ports, Thunderbolt 3 or 4 ports, eSATA ports, DVI outputs, or a VGA connector. Both motherboards lack PS/2 ports, making them reliant on modern USB peripherals.

The ASRock B850M Pro RS and Asus Prime B840M-A offer similar connector options, but there are some differences in their expansion capabilities. The ASRock B850M Pro RS provides more USB 3.2 Gen 1 ports (4) through expansion, compared to the Asus Prime B840M-A's 2. Both motherboards offer 4 USB 2.0 ports and 4 USB 3.0 ports through expansion. Additionally, both have 4 SATA 3 connectors for storage devices and 3 M.2 sockets for high-speed SSDs.

When it comes to fan headers, the ASRock B850M Pro RS has 5, offering more flexibility for system cooling compared to the Asus Prime B840M-A, which has 4 fan headers. Both motherboards are equipped with a TPM (Trusted Platform Module) connector, but neither includes U.2 sockets or mSATA connectors. Both also lack SATA 2 connectors, meaning all SATA ports are of the faster SATA 3 variety.

Overall, the ASRock B850M Pro RS has a slight advantage in terms of USB 3.2 Gen 1 ports through expansion and fan headers, while the Asus Prime B840M-A offers fewer of these connectors.

The ASRock B850M Pro RS and Asus Prime B840M-A offer different configurations of expansion slots. The ASRock B850M Pro RS includes 1 PCIe 5.0 x16 slot, 1 PCIe x4 slot, and no PCIe 4.0 or PCIe 3.0 x16 slots. It also lacks PCIe x1, PCI, PCIe 2.0 x16, and PCIe x8 slots. In contrast, the Asus Prime B840M-A has 1 PCIe 4.0 x16 slot, 2 PCIe 3.0 x16 slots, and no PCIe x4 or PCIe x8 slots. It also has no PCI, PCIe 2.0 x16, or PCIe x1 slots.

Both motherboards feature a similar selection of high-speed slots, but the ASRock B850M Pro RS stands out with its PCIe 5.0 x16 slot, which the Asus Prime B840M-A lacks. On the other hand, the Asus model offers more PCIe 3.0 x16 slots, with a total of two, compared to the ASRock’s single PCIe 5.0 x16 slot.

In summary, the ASRock B850M Pro RS supports newer PCIe 5.0, while the Asus Prime B840M-A provides more PCIe 3.0 x16 slots. Both boards are limited in other expansion options, with no PCIe x1 or PCI slots available on either motherboard.

Both the ASRock B850M Pro RS and Asus Prime B840M-A feature 7.1 audio channels, providing support for high-quality audio output. Neither motherboard has an S/PDIF Out port, so digital audio output via that method is not available on either board. Both models also include 3 audio connectors, allowing for various audio input and output configurations.

There are no differences between the two products in terms of audio specifications. Both offer the same audio channels, lack an S/PDIF Out port, and have the same number of audio connectors.

Overall, the audio capabilities are identical between the ASRock B850M Pro RS and the Asus Prime B840M-A, with no significant distinctions to note.

Both the ASRock B850M Pro RS and Asus Prime B840M-A support RAID 1 and RAID 10 (1+0), providing options for redundancy and performance configurations. Neither motherboard supports RAID 0+1. However, there is a key difference in their support for RAID 5. The ASRock B850M Pro RS does not support RAID 5, while the Asus Prime B840M-A does.

Both motherboards support RAID 0, allowing for performance-oriented configurations with multiple drives. Aside from this, their RAID capabilities are otherwise quite similar, with both providing RAID 1 and RAID 10 support but differing on RAID 5 support.

In summary, while the RAID features of both motherboards are largely the same, the Asus Prime B840M-A has the advantage of supporting RAID 5, which the ASRock B850M Pro RS lacks.