x370-F MB claims PCIE 4.0 but Samsung 990 Pro NVME is running at Pcie 3.0

[Dan033045]

Processor is Ryzen 5700G, is that throttling down the PCIE speed?

Samsung magician claims that Pro 990 is running at PCIE 3.0 speed and I should update the drivers.

All the motherboard drivers are current.

[Dan033045 · Accepted solution]

I got the answer from ASUS support, RYZEN 5700g runs PCIE at 3.0, not 4.0, This also affects the M.2 slots

[thumpboom]

So the Pcie 4.0 x16 slot will only run at pcie 3.0 x4 - ??  As well for the M.2 4.0-? Asus advertises the AMD board as having 4.0 connections -  - but they never say except for AMD 5700G or is it all Amd cpu's -? Sounds like false advertising to me

[Dan033045]

The problem is not the motherboard, it is the 5700G (with integrated Graphics) CPU which is restricting the PCIE bus to gen 3 speed. The 5700X and 5800X CPUs are all gen 4 PCIE. The 5700G technical spec sheet does state PCIE Gen 3 but I was not aware of that when I purchased that CPU. I was of the impression that it only impacted the integrated video PCIE speed and not the M.2 speed or the x16 slots. I wanted the integrated graphics to avoid buying a GPU card since my previous one died. I just bought a new GPU card just to increase my M.2 speed for a Samsung 990 PRO m.2 NVME SSD. Since I do a lot of video editing and COMPRESSING, I will most likely now buy a 5800X processor as well since it is better performing than the 5700G CPU. 

[thumpboom]

Do you think setting Bios to Bifurcation, splitting x16 to 2 x8s would make a positive difference  or would it even work-?  Wonder if it would turn the pcie 3.0 x4s to x8s

[Dan033045]

Bifurcation would not change the PCIE level to 4 from the slower level 3 that the CPU sets. Also, this motherboard does NOT support bifurcation. I did research this earlier, check out this link: [Motherboard] Compatibility of PCIE bifurcation between Hyper M.2 series Cards and Add-On Graphic Ca...,

[Dan033045 · Accepted solution]

After installing and using a second Discreet Graphics card and disabling the integrated GPU on the 5700g, the PCIE slot STILL runs at 3.0 rather than 4.0. The new PCIE 4.0 graphics card is also running at PCIE 3.0.

It is the CPU itself and not just the integrated GPU of the 5700G which is controlling the PCIE slot speed.  

Note that the X570 chip is connected through 4 lanes of the PCIE bus so anything connected to the X570 chip is restricted to the slower PCIE 3.0 speed which is half of the PCIE 4.0 speed.

Since the RYZEN I/O is controlled by the CPU including the X570 Chip, the only way to get full PCIE 4.0 speed anywhere on the motherboard is to replace the CPU with a different model.

[firelordling]

Amd took away pcie 4 support for x370f and another board a few years ago in a bios update. Was pretty feels bad that they later put out a bios update offering support for newer cpu chips tho. 

[firelordling]

In 2019 AMD took away support  for the 370 boards to run pcie 4 because allegedly some manufacturers boards were having trouble so they just scrubbed it for all. This was a bios update.  However it seems a little planned obsolescence-y.