Chapter 4 · Motherboard and Hardware Communication

Practical Lab: Exploring Motherboard Info

5 min read

Objective

Find out what is inside your own PC: the board, the chipset, the BIOS, the devices, their interrupts and their power states. You only look. Nothing in this lab changes any setting.

Time: 25–30 minutes
You need: A Windows PC. No extra software is required. (Two free optional tools are named in Part 5.)

What to Open

ToolHow to open it
System InformationPress Win + R, type msinfo32, press Enter
PowerShellPress Win, type PowerShell, press Enter (normal, not admin)
Device ManagerPress Win + X, then choose Device Manager
Command PromptPress Win, type cmd, press Enter

Part 1: Who Made My Motherboard? (System Information)

Open msinfo32. On the System Summary page, find these lines and write them down:

  1. BaseBoard Manufacturer: ________________
  2. BaseBoard Product (model): ________________
  3. BIOS Version/Date: ________________
  4. BIOS Mode (Legacy or UEFI): ________________
  5. Processor: ________________
  6. Kernel DMA Protection (from Section 4.5): ________________
  7. Secure Boot State: ________________

(On some PCs the BaseBoard lines are blank. That is normal for laptops from some makers.)

Part 2: Ask PowerShell (Same Facts, Another Way)

Type each line and press Enter:

Get-CimInstance Win32_BaseBoard | Select-Object Manufacturer, Product, SerialNumber
Get-CimInstance Win32_BIOS | Select-Object Manufacturer, SMBIOSBIOSVersion, ReleaseDate
Get-CimInstance Win32_Processor | Select-Object Name, MaxClockSpeed, ExtClock, NumberOfCores

Look at the third command. Fill in:

  1. MaxClockSpeed (MHz): ________________
  2. ExtClock (the base clock, BCLK, from Section 7.2): ________________ MHz
  3. Multiplier = MaxClockSpeed ÷ ExtClock: ________________

Does 100 MHz × multiplier give about the same number as your CPU's advertised speed? Great: that is the formula from Section 7.

Part 3: The Hidden Map of Your PC (Device Manager)

3A. See the tree. In Device Manager choose View → Devices by connection. Open the first big branch (usually ACPI x64-based PC), then keep opening PCI Express Root Complex. You are looking at the bus tree from Section 2:

ACPI x64-based PC
 └─ Microsoft ACPI-Compliant System
     └─ PCI Express Root Complex
         ├─ PCI Express Graphics (your GPU)
         ├─ NVM Express Controller (your SSD)
         └─ ...more devices under the PCH...
  1. How many PCI Express items can you see? ________________
  2. Is your SSD listed under the CPU's root port or under the chipset? ________________

3B. See the interrupts. Choose View → Resources by type. Open Interrupt request (IRQ).

  1. How many IRQ entries have a negative number (that means MSI, Section 3.3)? ________________
  2. Which device uses IRQ 1 (hint: keyboard)? ________________

3C. See the I/O ports and memory windows. On the same view, open Input/output (IO) and Memory.

  1. What port range does the keyboard use (Section 6.3)? ________________
  2. Find one big Memory range owned by your graphics card: ________________

3D. See USB. Choose View → Devices by type and open Universal Serial Bus controllers.

  1. How many "USB Root Hub" lines are there? ________________
  2. Does any controller say xHCI (that is the USB 3 type)? ________________

Part 4: Power States (Command Prompt)

powercfg /a
  1. Which sleep states are available? (S3, Modern Standby, Hibernate...) ________________
  2. Which states say not available, and why? ________________

Part 5 (Optional): Free Third-Party Tools

These are not part of Windows. Download them only from their official websites.

ToolLook atWhat you will see
CPU-ZMainboard tabBoard model, chipset, BIOS date, PCIe link width and speed (for example "x16 @ Gen4")
HWiNFO (Sensors only)Voltage and temperature rowsThe +12 V, +5 V, +3.3 V rails (Section 5), CPU voltage (VCore), and temperatures

Try this: In CPU-Z's Mainboard tab, click Run render test next to Graphic Interface. The PCIe speed changes from a low idle speed to full speed (the PC saves power, Section 5).

What Should Happen

  • Part 1 and 2 give the same board and BIOS facts.
  • Part 3 shows a tree that matches Section 2: GPU and SSD near the top, USB, SATA and network behind the chipset.
  • Part 4 shows your PC's supported sleep states.

Interpretation Guide

What you seeWhat it means
BIOS Mode: UEFIModern firmware (Chapter 5)
Many negative IRQ numbersDevices use MSI. Normal and healthy
Kernel DMA Protection: OnYour IOMMU protects memory from plug-in devices
powercfg /a shows "Standby (S0 Low Power Idle)"Your PC uses Modern Standby, not S3
powercfg /a shows "Hibernation has not been enabled"S4 and Fast Startup are off; powercfg /h on turns them on
GPU PCIe link shows x8 or lowerLanes are shared with another slot (bifurcation, Section 2.3)
BIOS date is very oldAn update may fix bugs, see the safety rules in Section 8.3
ExtClock = 100A standard base clock

Follow-Up Questions

  1. In Part 3A, which devices are connected through the PCH? How can you tell from the tree?
  2. Your PC says S3 sleep is not available but Modern Standby is. What does that mean for how "sleep" works on your laptop?
  3. Why do devices with MSI show a negative number instead of a small IRQ number?
  4. If your multiplier is 45 and ExtClock is 100, what happens to the multiplier when the PC is idle? (Think about P-states in Section 5.5.)
  5. Name three facts from this lab that you could not have learned from just looking at the outside of the PC.