Question M.2C Slot on Gigabyte X570 Aorus Ultra, providing 1/2 the bandwidth for a NVME PCIe 3.0 SSD

[galley]

I understand that M.2C on my X570 Aorus Ultra is not the speed of M.2A & M.2B
but, i think i am getting 1/2 the speed I should be getting when inserting a Samsung 970 EVO 3.0 SSD in M.2C
If i am wrong, please explain
Current Configuration:
Gigabyte x570 AORUS ULTRA, Ryzen 9 5900x
M.2A: 1 x Samsung 980 PRO 4.0 SSD
M.2B: 1 x Samsung 980 PRO 4.0 SSD
M.2C: 1 x Samsung 970 EVO 3.0 SSD
Slot X8: Gigabyte GT 730 PCIe 2.0 Rev 3 GUI
Hard drives connected to SATA 0-3
SATA 4 & 5: Not Used so lanes are free for M.2C
Slots PCIeX16 & PCIeX4 Empty

Results:
M.2A: 1 x Samsung 980 PRO 4.0 Result: PCIe 4x 16- Good
M.2B: 1 x Samsung 980 PRO 4.0 Result: PCIe 4x 16 - Good
M.2C: 1 x Samsung 970 EVO 3.0 Result: PCIe "2"x 8.0 - VERY BAD (50% bad from what SSD should be providing)

Test of M.2C - put the NVME SSDs in different M.2 Slots, to see the results:
M.2A: 1 x Samsung 980 PRO 4.0 Result: PCIe 4x 16 - Good
M.2B: 1 x Samsung 970 EVO 3.0 Result: PCIe "4"x 8.0 - Good, Appropriate for 3.0
M.2C: 1 x Samsung 980 PRO 4.0 Result: PCIe 2x 16 - Appropriate for a 980 PCIe 4.0 in M.2C

Thou I believe that Gigabyte advertises that all 3 x M.2 will provide full 4.0 - i am not concerned for this and didn't expect this when i bought the board.

Question:
Should I not be getting 2ce the bandwidth of M.2C with 1 x Samsung 970 EV 3.0 (about 1/2 the bandwidth of a 980 PRO 4.0? 4x 8.0 ? and not 1/2 speed of what the 970 is capable of if placed in a 3.0 M.2 Socket?
Thank you for your time.
Hope someone can help.

 

[Colif]

See note at bottom of page 21 of manual

The M2C_SOCKET connector supports up to PCIe x2 SSDs only.

https://download.gigabyte.com/FileL...1002_e.pdf?v=953e5d201f03f509be6d42af393f01b2
as per this same question