A recent development for AMD’s AM4 platform that has provoked some level of distrust, e-raging and disappointment amongst the technology community. Luke Larsen at Digital Trends has published an article highlighting the fact that the impending launch of the cost-optimized B550 chipset for desktop platforms will not contain support for legacy Ryzen processors. Additionally, AMD has confirmed that they will not be supporting the upcoming Ryzen 4000-series CPUs on prior platforms which use an older chipset.
What many have quickly forgotten is the fact that the introduction of support for newer processors on legacy platforms required making concessions to the functionality of the BIOS. When MSI reissued the B450 Tomahawk with twice the flash capacity for the BIOS, the need to do this highlights the absence of foresight from many of the predominant motherboard manufacturers. It’s been a long time since Intel has supported four or more generations of a processor using a unified socket. The 16MB standard-issue flash ROM has traditionally provided a sustainable baseline for enabling up to two generations of processor support.
While AMD has made good on their word related to the continued use of a singular socket for desktop platforms, the need to set a demarcation line for future supported processors has less to do with the socket and associated chipset and more about the potential brand damage incurred by trying to support 5 series of processors with limited flash capacity (28nm APUs, Zen, Zen+, Zen2, and Zen3). Prior concessions made within older platforms required either reducing the presentation layer or supported feature sets that are accessed within the BIOS. Realistically, the number of potential customers that are going to install an A-series APU or first-generation Zen CPU (as an example) into a B550 motherboard should be zero.
We’re not dismissing the frustration or disappointment that people who paired a Zen2 CPU with an X470/B450 chipset may be feeling. For motherboard reissues with 32MB of flash capacity, such as the MSI Max-series boards, it may be possible to make some trade-offs to make it work. A similar multi-step process could be used to provide support with a number of constraints. A two-step BIOS update process, while adding some complexity and risk, could address the limitations in a fair manner. A theoretical example of this would be:
- The BIOS on the older motherboard (300-series or 400-series chipset) is initially flashed to the latest “GUI Lite” iteration that supports the two most recent generations of processors. The current generation CPU (Ryzen 3000-series – non-G) is installed.
- With the current generation CPU in place, a subsequent BIOS comes out for the Ryzen 4000-series processors. The second flash removes support for the Ryzen 2000-series entirely.
While this would provide a balanced compromise for customers that intended to leverage their existing motherboard, there are also risks to AMD and its partners. Extensive testing of the VRM configurations on various X570 boards has been performed at a number of sites. Roman Hartung’s conclusion on such deficiencies may be further amplified when attempting to utilize an older motherboard that wasn’t designed with sufficient headroom for stable power delivery to processors exceeding a legacy power design target.
We don’t know the specifics on the Ryzen 4000-series processors at this point. We do know that X570-based motherboards should have been designed to handle an up-to-125W TDP processor and be capable of handling the associated power draw with sufficient heat dissipation to maintain ideal operations. It’s also a fair assumption, based on lessons learned by powerful reporting about deficient X570 VRM implementations, that the launch of B550-based motherboards would be designed to the same specification with a lower risk of deficiencies for the power implementation.
Although the B550-based motherboards are expected to be less expensive than X570-based motherboards, they won’t be cheaper than non-pandemic-priced B450 motherboards. Following the current best-value route with a B450-based motherboard + AF-series CPU would already exclude the B550-based motherboards from contention. There’s still a path available for those who want to future proof their build by spending additional money on an X570 motherboard which will support prior and current generation processors.
Those in the AM4 ecosystem now understand the burn that buyers of first-generation Threadripper felt. SP3 is still the socket of choice for this platform. The uptick in TDP and power requirements for the higher end of Threadripper 2000-series processors limited the upgrade path of early adopters. Threadripper 3000-series processors mandated the acquisition of a new motherboard. However, there wasn’t a prior assertion that the socket would remain universal for five years. The cost containment involved in maximizing profit on motherboards appears to be the predominant factor in the dramatic shift in approach for B550. AMD would benefit from mandating additional requirements for partners to follow if the successor to AM4 is intended to have a comparable lifecycle. Although the associated costs would be passed on to customers, the potential for unjustified outrage or potential brand damage can be proactively addressed.