SMI300XS Questions and Answers

Thepower cableis the only cable that isnot a data cablewhen connecting an AOM card to the motherboard.

Cable Functionality Breakdown:

A (Power Cable) → NOT a data cable

Supplies electrical powerto the AOM card.

Doesnot transmit databetween components.

B (MCIO Cables) → Data cables

These cablestransmit high-speed NVMe data.

C (JNCIS1) → Data cable

This interface is used formanagement and communication.

D (SAS Cable) → Data cable

Used fordata storage connections.

Official Documentation Reference:

Supermicro AOM Expansion Module Guidestates that thepower cable is the only non-data cablein AOM installations.

When reinstalling theNVMe backplane, several critical cables must be properlyreconnectedto ensure the system functions correctly.

Required Connections:

SATA Cable→ Some NVMe backplanesalso support SATA drives, requiring SATA connectivity.

Power Cables→ The NVMe backplanerequires direct powerto enable SSD operations.

MCIO Cables→ These cables providehigh-speed data connectivitybetween the NVMe drives and the motherboard.

54-Volt Power Cable→ Thissupplies direct powerto the NVMe backplane foroptimal performance and stability.

Why other options are incorrect?

B (Only SATA cable)→ NVMe backplanes usePCIe-based storage. While SATA connectionsmayexist,they are not the only required cables.

C (Only MCIO cables)→ While MCIO cables are necessary for PCIe-based NVMe drives,power cables must also be reconnectedfor the system to function.

D (Only power cables)→Data communication would failwithout MCIO connections, rendering the systemunable to detect NVMe drives.

Official Documentation Reference:

Supermicro NVMe Service GuideandAS-8125GS-TNMR2 Installation Manualemphasize thecorrect reinstallation of power and data cablesto avoidhardware malfunctions.

Components Located on Top of the Motherboard in Supermicro MI300X Systems

Fans and Fan Shrouds (Option A)

These are installedabove the motherboardtodirect airflow over the components.

Fan shrouds help focus airflow, ensuringefficient cooling of CPUs and GPUs.

Support Bar and AOM Brackets (Option B)

Thesupport bar reinforces the motherboard tray, preventing flexing.

AOM bracketshold optionalnetworking or RAID expansion modules.

Heatsinks and CPUs (Option C)

Large heatsinks are mounted on top of the CPUsto dissipate heat.

These ensureoptimal thermal managementof high-performanceAMD MI300X GPUs and processors.

Why Option D (DIMM Modules) is Incorrect?

❌DIMM modules (memory sticks) are installed in slots beside the CPU, but they arenot physically above the motherboardin a way that they could be considered a top-mounted component.

Official Documentation Reference:

Supermicro AS-8125GS-TNMR2 System Overviewconfirms thatfans, heatsinks, AOM brackets, and support bars are mounted on top of the motherboard.

Understanding MCIO Cables in Supermicro MI300X Systems

MCIO (Multi-lane Cable I/O) connectorsare used forhigh-speed data transmission between the motherboard and NVMe SSDs or PCIe devices.

These connectorsmust be handled carefully, as improper removal cancause pin damageorpermanent failure of the interface.

How to Properly Unlock and Release MCIO Cables

Locate the release levers on the MCIO connectors

Each MCIO connector has asmall built-in release leverthat locks it in place.

Press down on the release levers

This disengages the locking mechanism andallows the cable to slide out easily.

Gently pull the MCIO cable straight out

Do not pull at an angleas it can damage thehigh-density connector pins.

Why Other Options Are Incorrect?

A (Pull really hard)→ Forcing the connector without releasing the latch canbreak the MCIO pins or damage the motherboard socket.

B (Remove screws)→ MCIO cablesdo not use screws; they have built-in locking mechanisms.

D (Loosen bolts)→ There areno boltssecuring MCIO cables; only therelease lever is needed for unlocking.

Official Documentation Reference:

Supermicro AS-8125GS-TNMR2 Motherboard Manualstates thatpressing down on the release levers is the correct method to unlock MCIO cables.

Themidplane in Supermicro MI300X GPU systemsis responsible for interconnecting several system components. The twoprimary cablesthat must be removed before handling themidplaneare:

I2C Cable (Inter-Integrated Circuit Cable)

This cable is used forsensor data, system monitoring, and thermal control.

If not disconnected, it couldsnap or cause sensor miscommunicationbetween the motherboard and the backplane.

Power Cable

This cablesupplies powerto the midplane andmust be disconnected before removalto avoid electrical damage.

Removing the midplanewhile power cables are still attachedcould short-circuit the system.

Why is this step necessary?

Supermicro's official documentation states that both the I2C and power cables must be disconnected before handling the midplane.

Failure to remove these cables properly can cause permanent damage to connectors and the system board.

Official Documentation Reference:

Supermicro AS-8125GS-TNMR2 Maintenance Manualconfirms thatdisconnecting the I2C and power cables is mandatory before midplane removal.

Theyellow warning labelis a critical indicator toprevent damagewhen servicing themidplane and ribbon cable connections.

Reason for Warning Label:

Theflat panel/ribbon cable is delicateand isconnected between multiple system components.

If themidplane is removed first, itstretches and applies force on the ribbon cable, leading to:

Broken cable connectors

Torn ribbon cable

System interface failure(front panel controls, LED indicators, or data communication)

Why other options are incorrect?

A (Cable is hot)→ Ribbon cablesdo not generate heatand thisis not the purpose of the warning label.

B (Remove after midplane)→ Thecable must be removed BEFORE the midplane, not after.

C (Optional removal)→It is mandatory, not optional, to prevent damage.

Official Documentation Reference:

Supermicro AS-8125GS-TNMR2 Maintenance Manualstates thatremoving the flat panel/ribbon cable firstisa required stepbefore handling the midplane.

Thecorrect order for removing trays before midplane removalis:

Disengage the PCIe tray first

This tray must be removed first becauseit provides access to the underlying system components.

Remove the GPU tray

TheGPU tray sits between the PCIe and motherboard traysand must be disengaged after PCIe components are cleared.

Remove the motherboard tray last

The motherboard tray isthe final component before midplane removal.

Removing it lastensures full accessto the system componentswithout obstructing critical connections.

Why other options are incorrect?

B (Motherboard before GPU tray)→ The motherboard tray must be removedlastto avoid disconnecting system-critical connections too early.

C (Motherboard tray first)→ Removing the motherboard firstrisks damagingPCIe and GPU components.

D (GPU tray first)→ TheGPU tray is dependent on the PCIe tray being removed first, making this order incorrect.

Official Documentation Reference:

Supermicro AS-8125GS-TNMR2 System Removal Guideoutlines the correct order fortray disengagement before midplane removal.