Gigabyte B550 Vision D M2B_SB understanding

[Shou Miko]

On page 20 in the manual I am reading the note for the M2B_SB where it's stated "The PCIEX4 slot shares bandwidth with the M2B_SB connector. The PCIEX4 slot becomes unavaliable when a device is installed in the M2B_SB connector"


Link: https://download.gigabyte.com/FileList/Manual/mb_manual_b550-vision-d_1001_200616_e.pdf

This is fine and understandable but I guess since the board only have 4 SATA ports connecting a SATA based M.2. SSD won't cause any issues in the board by disabling any of the 4 SATA ports or am I wrong?

 

[tabascosauz]

Can't say for sure, but in past AM4 boards the vendors have been pretty clear about warnings on specs pages when M.2 SATA disables board SATA ports. They haven't really run into this issue before, because previously a lot of the AM4 boards' secondary M.2s didn't support SATA, only x2 NVMe. I feel like Gigabyte would have disclosed that limitation if it really was the case.

The PCIe bandwidth sharing is an issue that traditionally stems from the use of the Promontory PCH in X370/B350/X470/B450. B550 is based off the same design; that's why you get either bandwidth sharing or half-width x2 M.2 PCIe on some of these boards.

On a side note, I think the orange SATA port also supports SATA DOM.

 

[Shou Miko]

@tabascosauz i forgot about the sata dom and I hope that's the one it will be disabled because how many uses that port?

I guess only Gigabyte can answer this question but I thought to give it a shot here on TechPowerUp because there are a lot of friendly and wise people here.