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Updating the BIOS on your pre-X570 motherboard could break PCIe 4 support

(Image credit: Asus)

Heads up folks, Asus has begun pushing out BIOS updates for some of its X470 and X370 motherboards that, among other things, removes support for PCI Express 4.0 on certain models.

To be clear, Asus is not being the least bit nefarious. Here's the deal—prior to the launch of AMD's Zen 2 processors (otherwise known as third-generation Ryzen, or Ryzen 3000), AMD's hardware partners had the green light to add PCIe 4.0 support to existing motherboard models (read: pre-X570 motherboards), at each manufacturer's discretion.

As a result, some higher end motherboard models that met the more stringent signaling requirements of PCIe 4.0 received BIOS updates to support the feature. That mean users could install one of those newfangled PCIe 4.0 SSDs and enjoy the full performance benefits, with read speeds in the neighborhood of 5,000MB/s.

However, AMD reversed course at the 11th hour, telling its hardware partners they needed to block support for PCIe 4.0 on all pre-X570 motherboards. AMD's reasoning basically boils down to wanting to eliminate confusion.

"This is an error we are correcting. Pre-X570 boards will not support PCIe Gen 4. There's no guarantee that older motherboards can reliably run the more stringent signaling requirements of Gen 4, and we simply cannot have a mix of 'yes, no, maybe' in the market for all the older motherboards. The potential for confusion is too high," Robert Hallock, AMD's senior technical marketing manager, explained in a Reddit post.

"When final BIOSes are released for third-gen Ryzen (AGESA 1000+), Gen 4 will not be an option anymore. We wish we could've enabled this backwards, but the risk is too great," Hallock added.

Hallock conceded that some users might choose to stock with a beta BIOS enabling PCIe 4.0 on X470 and X370 motherboards once the final updates arrive, but warned "performance and stability cannot be guaranteed."

(Image credit: Asus)

Fast forward to now and that is the exactly the choice some Asus motherboard owners face. During the past week, Asus has issued PCIe 4.0-breaking BIOS updates for at least three pre-X570 models. They include the ROG Strix X470-I Gaming (X470), Crosshair VII Hero (X470), and Crosshair VI Hero (X370).

Should you update? If things are running fine, you may be find it best to stick with your current BIOS version. However, other listed features include "improve system performance" and "fixes a compatibility issue with Destiny 2."

If either of those matter, by all means, grab the latest BIOS and wave goodbye to 5,000MB/s read speeds (not that it matters for gaming). Otherwise, it's not like your PC is going to blow up if you stick with your current BIOS version. Those PCIe 4.0 SSDs will still work in your motherboard as well, just at lower speeds.