B850M-X VRM£

Based on the similarities between B650M-H/M.2+ (Plus is important here) and the new B850M-X, I'm going to guess that they share a similar (or even the same) VRM setup.

These are the only AsRock boards where the second m.2 NVMe slot is wired directly to the CPU.

According to TechSpot article, they're 50A stages, so 6 * 50 = 300A.
In theory, it should be more than enough to run even the 170W TDP (230W PPT) CPUs like the 9900X and 9950X.

Of course, they will be driven harder than VRMs on higher end boards with 8 or even 12 stages, but as long as you have adequate cooling, I imagine they'll be fine.

It's just a choice they make. They route 4 CPU PCIe lanes to the second PCIe slot in their other motherboards, and so the second m.2 NVMe slot is wired to the chipset. Not a huge deal for most people. If you absolutely need the second NVMe to be directly connected to the CPU, you can always just buy a PCIe to m.2 NVMe card. They're not that expensive. I have a couple of StarTech ones.

I don't know why AsRock doesn't publish the VRM implementation details. It's not like most people here work for AsRock or anything like that. Do other companies publish their VRM implementation details? For the most part, we have to depend on tech websites that buy them and manually gather information, by removing the heatsinks and possibly even analyzing the circuit board designs.

PS: Maybe I misunderstood your question.
AM5 CPUs, like the 7000-series (Raphael) and 9000-series (Granite) have 28 PCIe lanes.
4 are used to connect to the chipset. So 24 left.
16 are used for the main PCIe slot, usually used for a GPU). So 8 left.
4 are used for the main m.2 NVMe slot. So 4 left.
What to do with this final 4 lanes? Route it to another m.2 NVMe slot, or to another PCIe (x4) slot.
Not a huge deal either way. It's just a choice they make, and something consumers should research when making purchasing decisions.

Of course, most consumers are clueless, so....



Edited by eccential - 18 Feb 2025 at 8:01am

PCIe lanes are almost generic.

CPU even has the ability to split them differently.
For example, the first 16 lanes can be split into x8/x8, or even x4/x4/x4/x4 (not all CPUs can do this).

So you can actually install multiple NVMe drives onto the big x16 slot using a special bifurcation adapter. I think AsRock even made one at some point.

I'm not sure if 4 lanes are absolutely reserved for the chipset, either.
Since a chipset isn't required (X600), it may even be possible to attach SEVEN NVMe x4 drives directly to the CPU, if a motherboard like that is made.