I have a dual Xeon board with Intel C602 chipset and two E5-2670 CPUs. The board comes with five PCIe 3.0 x16 slots and a PCIe 3.0 x4 slot; all of which are directly connected to the CPUs.
I added a PCIe 3.0 card to a x16 slot connected to the first CPU ("BSP") as well as another card to the x4 slot (also connected to BSP). In both cases I find the that they are downgraded to PCIe 2.0 speed.
# lspci -vvs 82:00.0 | egrep '(82:00|GT)'
82:00.0 Non-Volatile memory controller: Samsung Electronics Co Ltd NVMe SSD Controller SM981/PM981 (prog-if 02 [NVM Express])
LnkCap: Port #0, Speed 8GT/s, Width x4, ASPM L1, Exit Latency L1 <64us
LnkSta: Speed 5GT/s (downgraded), Width x4 (ok)
LnkCtl2: Target Link Speed: 5GT/s, EnterCompliance- SpeedDis-
# lspci -vvs 02:00.1 | egrep '(02:00|GT)'
02:00.1 Ethernet controller: Intel Corporation Ethernet Controller 10G X550T (rev 01)
LnkCap: Port #0, Speed 8GT/s, Width x4, ASPM L1, Exit Latency L1 <16us
LnkSta: Speed 5GT/s (downgraded), Width x4 (ok)
How may I assess why the link speed was downgraded and possibly rectify the problem?
downgraded
. In the BIOS, I changed all slots from2.0
to3.0
. Since then, only shortly after booting, I get a few btrfs read errors on multiple drives, which indicates some type of hardware problem besides the drives. The reads are corrected, and everything is fine until the next reboot. Are you noticing any issues that sound like this? Changing them back to2.0
has not fixed the problem. I have an identical system running3.0
just fine. – user1902689 Jan 7 '19 at 2:10