Strix X870E-E Gaming Wifi M.2 gen 5 and PCIe lane sharing

[BJBBJB]

All of my builds use ROG components and I have read the manual, but still unclear on this.

I have 2 Gen 5  M.2 SSD drives.   I am very familiar with lane sharing over the years.  

The manual says: M.2_2 & M.2_3 slots share bandwidth with PCIEX16(G5).  When M.2_2 & M.2_3 are occupied with SSD devices, PCIEX16(g5) will run X8 only. It is unclear to me if this means both or either?

The question is, if I only occupy ONE of those slots with a Gen 5 (say M.2_2) and put a Gen 5 in M.2_1 (should be no issue and no impact on this), does that config cut the video card speed to X8?

Or does putting a Gen5 drive in EITHER M.2_2 & M.2_3 trigger the speed reduction?

If so, I will put my boot Gen 5 in M.2_1 and my other Gen 5 in M.2_4 and it will run at Gen4 speed which I can live with. If someone can point me to a definitive explanation I would appreciate it. I know the table for my manual is has less parameters listed than the X870E Hero manual which is was discussed a lot. 

I also am trying to decode the detailed manual as to whether I need to use the rubber pads for a Crucial T705 M.2 4TB and a Tforce GC PRO Gen5 4TB.  I underside it is all about single side or double side but I cannot find that in the specs. to determine if they are. 

Thanks!

BJBBJB

[BJBBJB]

Did you use those rubber pads?  Still can't figure out if I should use or not?

BJBBJB 

[Tom017931]

Yea I left it how it was just removed the plastic peal on it

[BJBBJB]

That is some excellent info from both of you!  Thanks!   I have 4 SSD's for my next build so understanding all of the above I will have to either look at a different AMD build or look at Intel Boards. Since it is probably more creative than gaming not a huge deal if they fix some things in the next few months.

Just great info here and the chart too. Totally get it now.

Thanks,
BJBBJB

[Psamtik]

Replace "When M.2_2 & M.2_3 are occupied with SSD devices" with "When M.2_2 or M.2_3 are occupied with any SSD devices" and the confusion is cleared up. I thought the same as the wording  does make it could seem like only if both are filled, it reduces the performance of the x16 slot, but I can confirm that either one filled with any gen M.2, will reduce it to x8.

Also, there us a good chance that EXPO/DOCP/XMP will stop them working as well,  as even on the latest BIOS they still disappear for me. I decided that the loss in performance was annoying but not to big a deal that it was worth the effort of putting my X670E-F back in (which did allow for all 4 slots to be filled with GEN 4 at least, and keep the x16 at x16 ) and I just took the drive out of the 4x PCIe slot and added it to M.2_3.  I also do the ram timings manually so as to not loose the drives and get the ram performing as it should or better.