Question Help with how to pick AM5 motherboard that wont drop GPU to x8 while multiple M.2's are populated?

[sefybuns]

(Apologies ahead of time if this is very long) I've never built a PC before and I'm very confused about how X670E motherboards will be utilizing PCIe lanes with a 7950x, more specifically geared toward my use case though since not many people are using more than two M.2's.

I'll be running a more 'creator' specific build, and I'll immediately need to populate 3 SSD slots. My current plans are a 1TB 990 Pro for Windows + apps + unsorted, 2TB SN850X for games + mods, and an Acer Predator GM7000 4TB for 3D assets + textures + video editing stuff. Maybe I'll add another SSD down the line but that won't be for a little while.

Now I know that the 7950x has 24 PCIe lanes going to the CPU's motherboard connections, and the other 4 of the 28 total go to the chipset. For example: If the motherboard has 2 PCIe 5.0 x16 expansion slots (only one of which is populated) and 2 out of 4 SSD slots are PCIe 5.0 x4, will populating the 5.0 x4 SSD slots with 4.0 x4 NMVe's result in the GPU being run at x8?? Asking this only in the case of the motherboard manufacturer not having any sort of block diagrams, and in that case I'd like to understand how this architecture works.

From different forum posts, I've collected that the 7950x can only support so many PCIe 5.0 connections naturally so, but if I'm not running any PCIe 5.0 connections, does it even matter how I configure my SSD's?? If it does matter, would 3 total PCIe 5.0 connections on the motherboard be the sweet spot? Like would 4 used 5.0 slots with 4.0 hardware run the GPU at x8?

 

[Lutfij]

Welcome to the forums, newcomer!

You could look through this;

View: https://www.youtube.com/watch?v=pUUVW7wgR3s


As for a an example of a board with 3 M.2 SSD slots;
https://pcpartpicker.com/product/FcbRsY/asrock-b650m-pro-rs-micro-atx-am5-motherboard-b650m-pro-rs
is one example, but one of the M.2 slot will operate at Gen4x2 speeds while the other two will run at Gen5x4 and Gen4x4 speeds, respectively.

My question is, do you need all of those high end SSD's? Logically you won't be able to tell the difference in real world applications on a day to day basis, unless we're talking about going in and out of levels like games or loading data for content creation. The 990Pro is pointless IMHO, you could literally have the OS on a PCIe 3.0x4 SSD and you'll be fine.

To also mention, you didn't mention the rest of your build, nor your location nor your budget. We will need tat to help refine your build and follow up suggestions.

 

[Eximo]

PCIe speed and PCIe lanes are not directly related. If you hook up a PCIe 1.0 4x card, you still use 4x lanes on whatever PCIe revision.

The CPU has 24 lanes with the 4 connecting to the chipset, yes. The chipset has its own lanes, and in the case of X670E is connected to another chipset as well.

At that point you have many devices all competing for bandwidth, but not connections, to the CPU.

If you want all your drives to operate at full speed, then you would actually want to connect them to the CPU directly. 8x for the GPU, 2 4x SSDs in the other main x16 slot, and then the CPU reserved M.2 slot.

However, if your expectation of data usage is more typical. Just populate the drives into any M.2 slots you want that don't conflict with the x16 GPU option.

Basically, you will have to sit down with the motherboard manual for any board you like the look of to get full details. Newegg.com also does a decent job of laying it out on their specs tab.

This is the cheapest board that offers three 4x lane M.2 drives.

https://pcpartpicker.com/product/fCGbt6/asrock-x670e-pro-rs-atx-am5-motherboard-x670e-pro-rs

 

[sefybuns]

To also mention, you didn't mention the rest of your build, nor your location nor your budget. We will need tat to help refine your build and follow up suggestions.

Thank you for the reply!

My current build plan looks like this:

https://imgur.com/a/7E9TkOw

I'm in the US so the pricing/availability market isn't going to generally affect me too much. And my budget for the PC itself is about $3,600-$3,900, but combined with peripherals about $4,500±. Also, I'm positive I can drop the price down to the low $3,000's range, but I also am leaning towards buying a system and not thinking about upgrading it for 4+ years besides storage.

My specific reasoning for each part vary, but:

• AIO: I'd rather not with an air cooler for general noise, and even if I undervolt the 7950x I wanna be secure in knowing I can run my cpu for overnight rendering.
• 7950x: seen benchmark videos and it for sure isn't the best gaming CPU but it seems to hold it's own in 3D benchmarks
• X670E-A Gaming Wifi: Not entirely sure, that seems to be the most back-and-forth part for me in the build especially with the needing multiple SSD's and needing the full performance from my GPU.
• RAM: seen a lot about DDR5 being finicky on AM5, and I'll need a decent amount for video editing.
• SSD's: Need a lot of storage and am very specific about organization
• 4090: Could go with 4080 Super or even lower but the VRAM is absolutely essential and AMD GPU's just don't match up with RTX cards for 3D rendering.
• Case: Aesthetics, lol
• PSU: Will maybe eventually add HDD's in raid if I decide I reaaaaally need them

Also, I've began making money with 3D using my mac and as I've pushed it's limits I've realized I want/will eventually need a high end PC, I can only optimize in Blender so much.

My question is, do you need all of those high end SSD's?

About the SSD's, I definitely don't need top of the line and that's something I'll have to tune down in price. But for 3D and video specifically, opening unpacked projects and loading 8K textures and importing 4k renders to edit and color grade definitely adds up over a day or two and it's something I wanna pay no mind to.

 

[sefybuns]

However, if your expectation of data usage is more typical. Just populate the drives into any M.2 slots you want that don't conflict with the x16 GPU option.

Thanks for the reply I appreciate it!

I posted my build plan in my reply to Lutfij just now, but I'm currently planning on the Asus STRIX X670E-A Gaming Wifi, and the manual is a little plain in regards to block diagrams and suggested SSD configuring. It has 3 PCIe 5.0 slots total: 1 for GPU and 2 M.2 slots connected to the CPU. The last 2 M.2 drives connected to the chipset are PCIe 4.0 x4. It doesn't say if any ports share bandwidth between eachother, or anything like "If M.2_1 is used, then PCIe_1 will be used at x8".

The more important thing for me is to run the GPU at max performance, and since the manual is lacking, so do you think there'd be any issues with SSD and GPU bifurcation for this specific motherboard?

 

[Eximo]

The memory you picked was intended for Intel XMP. You want this instead:

https://pcpartpicker.com/product/DP...r5-6000-cl30-memory-f5-6000j3036g32gx2-tz5nrw

I think you would have to avoid the PCIe 5.0 M.2 slot farther from the CPU, or vice versa. The two 4.0 slots should be fine to use. But the manual doesn't make it clear. Easy enough to test when you get it, check your PCIe lane count on the GPU with GPU-Z and swap it if it drops to 8x.

Considering the board only offers a 4x x16 slot in addition to the main one, I don't think they had much in mind when it comes to interference with the GPU.

Honestly for rendering and stuff, the lane count isn't that important. It would have only a minor effect on high resolution/texture gaming.

I don't really agree with liquid cooling for profit seeking systems. Better to just get a really big air cooler.

https://pcpartpicker.com/product/xM...-argb-6617-cfm-cpu-cooler-pa120-se-white-argb

One failure mode of a liquid cooler is leaking, right on top of your 4090...

 

[Zerk2012]

Thanks for the reply I appreciate it!

I posted my build plan in my reply to Lutfij just now, but I'm currently planning on the Asus STRIX X670E-A Gaming Wifi, and the manual is a little plain in regards to block diagrams and suggested SSD configuring. It has 3 PCIe 5.0 slots total: 1 for GPU and 2 M.2 slots connected to the CPU. The last 2 M.2 drives connected to the chipset are PCIe 4.0 x4. It doesn't say if any ports share bandwidth between eachother, or anything like "If M.2_1 is used, then PCIe_1 will be used at x8".

The more important thing for me is to run the GPU at max performance, and since the manual is lacking, so do you think there'd be any issues with SSD and GPU bifurcation for this specific motherboard?

With what your using you have 24 PCIE lanes that can be used from the CPU so 16 GPU 2X X4 M.2's
The chipset M.2's are not a factor.


Total supports 4 x M.2 slots and 4 x SATA 6Gb/s ports*
AMD Ryzen™ 9000 & 7000 Series Desktop Processors
M.2_1 slot (Key M), type 2242/2260/2280 (supports PCIe 5.0 x4 mode)
M.2_2 slot (Key M), type 2242/2260/2280 (supports PCIe 5.0 x4 mode)

AMD Ryzen™ 8000 Series Desktop Processors
M.2_1 slot (Key M), type 2242/2260/2280 (supports PCIe 4.0 x4 mode)
M.2_2 slot (Key M), type 2242/2260/2280 (supports PCIe 4.0 x4/x2 mode)**

AMD X670 Chipset
M.2_3 slot (Key M), type 2242/2260/2280/22110 (supports PCIe 4.0 x4 mode)
M.2_4 slot (Key M), type 2242/2260/2280 (supports PCIe 4.0 x4 mode)

EDIT Delivering 28 lanes of on-chip PCIe®Gen5 (24 lanes usable when pairing with B650 or X670 chipset)
https://www.amd.com/system/files/documents/ryzen-embedded-7k-product-brief.pdf