X370 vs B350 vs SOC

KD5ZXG

Gawd
Joined
Mar 24, 2017
Messages
745
I'm running crossfire RX 480's on my ASUS Prime B350 Plus.
"fast" 16x-sized socket is offered directly from the Ryzen SOC.
"slow" 16x sized socket on this board branches off the B350,
offering only PCIe 4x2.0, sharing bandwith with both Ethernet
and SATA. NVMe is Direct from Ryzen, though I don't use it.
I should theoretically be able to plug an SATA or two into the
NVMe slot with adaptor or cable? Perhaps I've misunderstood.

I notice certain ASROCK B350's offer thier 4x slot directly off
the Ryzen, and therefore 4x3.0! NVMe moves to the B350
where it has to shares just 4 lanes with all other peripherals.

I notice photos of a Biostar mATX X370 that doesn't use a
single feature of X370 over B350. Just a marketing gimmick?

Going by the feature set of Ryzen's SOC, do we even need
a southbridge chipset? If you plug ethernet and such to the
provided USB3 ports, and SATA to the provided lanes. This
should free up enough lanes for 8x,8x,8x crossfire? Could
offer NVMe and a southbridge on an 8x riser, as an option.

So, what are X370 and X350 really offering that the Ryzen
SOC doesn't thoroughly cover? Either one seems an awful
waste of four PCIe lanes that could go to better purpose.
Some less obvious but still necessary support functions?
Perhaps sale of these chips covers licencing some AMD
code in the BIOS? I'm totally guessing now...

Please, someone who actually knows, jump in and correct
my ignorance on these matters!

-------

*FYI* my "Slow" 4x2.0 slot shares Samsung SATA SSD,
Toshiba 4TB, Ethernet and whatever. Still benches RX480
at better than 90% speed of the "Fast" slot. And together,
TimeSpy at 8088, which is same as others running X370.
But sometimes my crossfire seems to hesitate a frame or
two, when there is an SSD access. This is why I hope
my SATA drives might be adapted to the NVMe slot.

s-l1600.jpg
Sorta like this M2 NGFF to SATA, but NVMe 2x SATAs.
Does such a thing exist?
I don't care if BIOS doesn't check for 2nd SATA on the
unexpected lanes, as long as Windows still picks it up...
 
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Proof those NVMe 4x3.0 lanes could host a GPU.
PE4C-M4060A V4.1_1000.jpg
Price $200 a little ridiculous, Could buy two of the
Asrock B boards already configured 16x3.0,4x3.0.
Or any of several X370 that can optionally split off
8x of the SOC's 16x GPU lanes into 8x3.0,8x3.0.

Don't know that they need any bridge to hardwire
Ryzen SOC to a fixed configuration? Still trying to
understand what so important in B350 X370 that
we shouldn't put those 4x3.0 lanes to better use.
Like combine with NVMe to get another 8x3.0...

SOC gives us DDR4, PCIe3.0, USB3.0, SATA.
What essentials are missing, besides voltage
regs and BIOS?

----

Nevermind SOC SATA. Lost it when decided to
abuse 4x NVMe lanes. Still got USB3.0 for boot.
Yes, at that point its a bit silly, but not impossible.
 
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