B850M-X VRM£
Printed From: ASRock.com
Category: Technical Support
Forum Name: AMD Motherboards
Forum Description: Question about ASRock AMD motherboards
URL: https://forum.asrock.com/forum_posts.asp?TID=97783
Printed Date: 06 Sep 2025 at 9:14am
Software Version: Web Wiz Forums 12.04 - http://www.webwizforums.com
Topic: B850M-X VRM£
Posted By: ATF
Subject: B850M-X VRM£
Date Posted: 17 Feb 2025 at 7:11pm
> 6+1+1 Phase Power Design, Dr.MOS for VCore
What's the amperage of the stages and why is this info not included?
https://www.asrock.com/MB/AMD/B850M-X/index.asp" rel="nofollow - https://www.asrock.com/MB/AMD/B850M-X/index.asp
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Replies:
Posted By: eccential
Date Posted: 17 Feb 2025 at 10:10pm
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.
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Posted By: ATF
Date Posted: 18 Feb 2025 at 4:36am
Why aren't all second M.2 slots wired to the CPU?
Do you know why Asrock isn't publishing the VRM info?
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Posted By: eccential
Date Posted: 18 Feb 2025 at 7:57am
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....
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Posted By: ATF
Date Posted: 19 Feb 2025 at 5:02am
Ah, I thought the 8 CPU lanes were only usable for NVMe.
Probably not a big deal indeed.
https://images.anandtech.com/doci/17585/SoC_26.png" rel="nofollow - https://images.anandtech.com/doci/17585/SoC_26.png
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Posted By: eccential
Date Posted: 19 Feb 2025 at 5:51am
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.
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