Gigabyte B550 UD AC Motherboard and using 2 M.2 SSDs

[AnimeAddict7]

Hello everyone, 

So, I am new to PC gaming and have my first ever Gaming PC right now. I am using a Ryzen 5 5600G processor with 16 GB of DDR4 3200Mhz RAM, I have an RX 6800XT in the top PCIE x16 slot on the motherboard. The system came pre-installed with a Gen 4 500GB M.2 SSD as the boot drive. sooooo... my question is, is it possible to use the other M.2 drive that is lower on the board that is tied to the chipset? the top slot that is populated says that it is tied to the CPU... I had heard that if you use more M.2 slots you hamper the performance of other PCIE things??? so I was wondering if I was to put a Gen 3 M.2 SSD in that bottom slot... (The bottom slot is only Gen 3, the top slot is Gen 4) would that be a terrible mistake? will that kill my performance of the RX 6800 XT?

The only other thing i could think of is to replace the boot drive with a larger Gen 4 SSD 

that seems really scary to me but maybe it's not that bad idk...

I am still learning and growing into the PC gaming community. I hope that someone here can educate me as I have tried looking stuff like this up but sometimes, I get confused. 


Thank you for reading this post I hope you all have a wonderful day. 

[RONOTHAN##]

1 minute ago, AnimeAddict7 said:

I had heard that if you use more M.2 slots you hamper the performance of other PCIE things???

This depends fully on how the motherboard wires everything. There are a few different ways things can be wired up:

1. Connected directly to the CPU
2. Connected directly to the CPU but wired through a switch with something else
3. Connected to the chipset
4. Connected to the chipset but wired through a switch with something else

Option 1 is what your top M.2 slot is, and that will not share bandwidth with anything.

 

Option 2 can share bandwidth with something technically. The main examples I can think of for this on B550 are motherboards like the B550 Master, which in order to get more PCIe Gen 4 M.2 slots drop the GPU to x8 operation rather than x16, and use those other 8 lanes for two different M.2 slots. This isn't necessarily how this would have to be wired up, it's very much possible for an M.2 slot and PCIe x4 slot to be wired to the same lanes and just switch which is active depending on what is connected at the time (server boards sometimes do this, and IIRC there are a couple AM5 boards that do this though I can't remember which ones specifically). This isn't what's happening in your case. 

 

Option 3 is what is happening for your 2nd M.2 slot. The SSDs go through the chipset and will have to share bandwidth with anything else connected to the chipset. This includes but isn't limited to SATA drives, USB devices, lower priority PCIe slots, etc. You would be limited to the maximum bandwidth from the chipset at any one time, in the case of B550 PCIe Gen 3x4, and therefore if you're trying to use everything at once you'll start to hit bandwidth limits and the SSD's peak performance will be lower than if connected directly to the CPU. If you aren't directly accessing multiple devices through the chipset at a time though (this is fairly uncommon in consumer workloads), this isn't likely to be a factor. 

 

Option 4 is almost identical to Option 3 except do to some chipset limitations sometimes a few SATA ports will have to be disabled if a certain PCIe/M.2 slot is populated. Your board doesn't do this, but a lot of other boards do it. 

 

TL;DR: Putting an SSD in the 2nd M.2 slot is going to do nothing to your GPUs performance. 

 

16 minutes ago, AnimeAddict7 said:

The bottom slot is only Gen 3, the top slot is Gen 4

Both slots are actually only Gen 3. The top slot may be capable of Gen 4, but because you're using a 5600G, that chip is designed to use PCIe Gen 3, so the slots are limited to it. PCIe is both forwards and backwards compatible though, so a Gen 4 drive will work just fine in a Gen 3 slot and vice versa, it's just that the max bandwidth will be limited to the slowest common speed. 

[AnimeAddict7]

5 minutes ago, RONOTHAN## said:

This depends fully on how the motherboard wires everything. There are a few different ways things can be wired up:

1. Connected directly to the CPU
2. Connected directly to the CPU but wired through a switch with something else
3. Connected to the chipset
4. Connected to the chipset but wired through a switch with something else

Option 1 is what your top M.2 slot is, and that will not share bandwidth with anything.

 

Option 2 can share bandwidth with something technically. The main examples I can think of for this on B550 are motherboards like the B550 Master, which in order to get more PCIe Gen 4 M.2 slots drop the GPU to x8 operation rather than x16, and use those other 8 lanes for two different M.2 slots. This isn't necessarily how this would have to be wired up, it's very much possible for an M.2 slot and PCIe x4 slot to be wired to the same lanes and just switch which is active depending on what is connected at the time (server boards sometimes do this, and IIRC there are a couple AM5 boards that do this though I can't remember which ones specifically). This isn't what's happening in your case. 

 

Option 3 is what is happening for your 2nd M.2 slot. The SSDs go through the chipset and will have to share bandwidth with anything else connected to the chipset. This includes but isn't limited to SATA drives, USB devices, lower priority PCIe slots, etc. You would be limited to the maximum bandwidth from the chipset at any one time, in the case of B550 PCIe Gen 3x4, and therefore if you're trying to use everything at once you'll start to hit bandwidth limits and the SSD's peak performance will be lower than if connected directly to the CPU. If you aren't directly accessing multiple devices through the chipset at a time though (this is fairly uncommon in consumer workloads), this isn't likely to be a factor. 

 

Option 4 is almost identical to Option 3 except do to some chipset limitations sometimes a few SATA ports will have to be disabled if a certain PCIe/M.2 slot is populated. Your board doesn't do this, but a lot of other boards do it. 

 

TL;DR: Putting an SSD in the 2nd M.2 slot is going to do nothing to your GPUs performance. 

 

Both slots are actually only Gen 3. The top slot may be capable of Gen 4, but because you're using a 5600G, that chip is designed to use PCIe Gen 3, so the slots are limited to it. PCIe is both forwards and backwards compatible though, so a Gen 4 drive will work just fine in a Gen 3 slot and vice versa, it's just that the max bandwidth will be limited to the slowest common speed. 

WOW!!! THANK YOU SOOOOO MUCH!!!!!

That was an amazing comment! 

I don't think I have ever had someone comment to me so thoroughly and explain these complex concepts to me!

Thank you so much!!! 

I really really really really appreciate you typing all this out to me and putting forth the effort to educate me on this subject


I will for sure be populating that M.2 slot as soon as I can 

Thank you so much again!!!