When working with Supermicro motherboards featuring integrated IPMI (like the X11 series), a common pitfall emerges: the KVM video remains black when onboard graphics are disabled while using a PCIe GPU. This behavior occurs because:

• IPMI's video capture hardware is physically wired to the onboard VGA output
• The BMC (Baseboard Management Controller) cannot intercept PCIe GPU framebuffer data
• Most server-grade GPUs don't support output redirection to IPMI

To confirm this architectural limitation, check your board's block diagram in the manual. For example, the X11SSL-F schematics clearly show:

[IPMI Video Path]
BMC → AST2500 → VGA Connector
              ↳ (No pathway to PCIe bus)

Option 1: Enable Onboard Video

1. Set JP1 jumper to enable onboard VGA (consult your board's manual)
2. In BIOS:

   Advanced → Chipset Configuration → Primary Display = "Onboard"

3. Keep PCIe GPU installed for host OS use

Option 2: GPU-Specific Workarounds

For NVIDIA Tesla/Quadro cards (Linux example):

# Force framebuffer console on GPU
echo "efifb: off" >> /etc/default/grub
echo "video=vesafb:off,efifb:off" >> /etc/default/grub
update-grub

Even with correct hardware setup, these IPMI settings often need adjustment:

# Check current video mode
ipmitool -I lanplus -H  -U admin -P password raw 0x0c 0x68 0x21

# Force VGA mode (hex values vary by board)
ipmitool -I lanplus -H  -U admin -P password raw 0x0c 0x68 0x11 0x00 0x03

For headless compute nodes where PCIe GPU is mandatory:

• Use serial console redirection instead of KVM
• Configure IPMI SOL (Serial Over LAN):

  ipmitool -I lanplus -H  -U admin -P password sol activate
  

• Consider HDMI/USB capture devices as last resort

When troubleshooting Supermicro's IPMI implementation, it's crucial to understand how the video subsystem works. The Baseboard Management Controller (BMC) typically captures video output through these pathways:

• Direct frame buffer access from integrated graphics
• Digital Video Interface (DVI) hotplug detection signals
• PCIe configuration space monitoring

In my testing with X11DPi-NT motherboard (BIOS 3.3), these configurations produced different results:

# lspci output comparison
00:02.0 VGA (onboard) - Disabled: No IPMI video
01:00.0 NVIDIA GPU - Active but not captured by BMC

The BMC firmware (version 01.72.00) logs showed:

VIDEO: No signal detected on VGA port
KVM: Keyboard/mouse packets received (0x3412 count)
FRAMEBUFFER: 0x0 resolution reported

Supermicro motherboards use JPG1 (or similar) for onboard VGA control. The behavior differs between generations:

For systems requiring both PCIe graphics and IPMI KVM:

1. Enable CSM support in BIOS
2. Set "Primary Display" to "Onboard"
3. Configure "Active Video Output" to "Auto Switch"

Sample ipmitool commands to verify:

ipmitool -I lanplus -H 192.168.1.100 -U admin raw 0x30 0x70 0x0c 0
# Returns 00 if onboard GPU is active
# Returns 01 if discrete GPU is active

Newer BMC firmware (v2.0+) supports PCIe frame buffer capture through:

# Enable PCIe capture (X12 generation)
ipmitool -I lanplus -H $BMC_IP raw 0x32 0x6a 0x20 0x00 0x00 0x01

For legacy systems, consider adding a dummy VGA plug to trick the hotplug detection:

#!/bin/bash
# Simulate VGA presence
echo 1 > /sys/class/graphics/fb0/device/hotplug