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Lenovo ThinkCentre M900 Tower (Magnesium)

Magnesium Front
ArcaOS license type


The Lenovo M900 tower computer is compatible with ArcaOS. Built-in video, sound, network, USB, serial port all function under ArcaOS 5.1. The computer features tool-free installation of SATA hard drives and an assortment of PCIe slots.


After you add the computer and optional CPU upgrade to the cart, proceed to the Accessories page to add PS/2 ports, parallel port, floppy drive, hard drive upgrade or a USB 2.0 card.


PS/2 Ports

This computer has optional PS/2 ports.

PS/2 Ports

Magnesium PS/2 Ports

PS/2 Ports: $75.00 USD

Parallel Port

This computer has an optional parallel port.

Parallel Port

Parallel Port

Parallel Port: $50.00 USD

USB 2.0 Card

This PCIe-X1 bus card provides USB 2.0 ports. You can use this card with USBEHCD.SYS to provide support USB devices.

USB 2.0 Card

Magnesium USB 2.0 Card

PCIe USB 2.0 Card: $75.00 USD

USB Floppy Drive

This external USB Floppy drive can be used to read and write 720K and 1.44M 3 1/2 inch floppy disks.

USB Floppy Drive

USB Floppy Drive

USB Floppy Drive: $50.00 USD

External WiFi

Using a travel router with a desktop can free you from a wired Ethernet connection. I use the Mango Travel Router to access local WiFi or my phone's hot spot. Mango comes with everything you need to connect to an access point.

Mango Travel Router

Mango Thumbnail

Mango Travel Router: $65.00 USD

In the past, I have also used a TP-Link AC750 Wireless Travel Router, an Asus RP-N12 Wireless N300 Range Extender, and a TP-Link Nano Router. I include a folder of URL links to the admin pages of each of these routers to make it easy to set up the first time.

Instructions and details about external WiFi: Travel Routers

Hard drive upgrade

The hard drive can be upgraded to a 2 TB drive. Either a hard disk or an SSD is available to upgrade.

Hard drive upgrade

Magnesium hard drive upgrade
Storage type

Icy Dock dual removable drive bay

The Icy Dock dual removable drive bay allows mounting one or two 2 1/2 inch drives. SATA hard drives and solid state drives (SSD) are supported. The drive can be ejected and replaced. Only SATA drives are supported. The computer must be powered down before ejecting the disk or data loss can occur.

Icy Dock dual removable drive bay

Icy Dock dual removable drive bay<

Icy Dock dual removable drive bay: $150.00 USD

Custom Orders

If you want to buy a customized version of this computer, fill out an order form and submit it to Blonde Guy. Blonde Guy will review your order and send you an invoice, payable using PayPal or any major credit card. If you prefer to pay by check, note that in the notes field of the order form, and I will e-mail you an invoice payable by check.

Enter the customizations you want on the computer in the notes portion of the order form.


Manufacturer: Model: ThinkCentre M900 Tower
Model number: 10FCS0AX00
Year introduced: 2015
CPU: Intel(R) Core(TM) i7-6700 CPU @ 3.40GHz
RAM: 16.0 GB
Hard drive: 1000 GB 3.5 inch SATA
Optional hard/solid state drive: 2000 GB SATA
Optical drive: Lenovo DVD-Multi player drive
Network: Intel Gigabit Ethernet using MultiMac32-E1000E driver
Audio: Intel audio with line out and line in using UniAud driver
USB ports: 8 (2 front, 6 back)
USB controllers: 0 UHCI, 0 OHCI, 0 EHCI, 1 XHCI
Video ports: VGA, DisplayPort

Physical Dimensions

Height: 16 inches
Width: 6.9 inches
Depth: 16.3 inches
Weight: 27.6 lbs

Power Consumption

Power consumption is 21 Watts, measured with the computer is booted to the desktop. With all CPU at 100%, the computer can consume about 60 watts. This computer consumes 1 Watt if it's plugged in, but switched off.

Disk Layout

The screenshot below is from a system that can dual boot Windows and ArcaOS.

Magnesium Disk Layout

ArcaOS version

ArcaOS 5.1.0 (August 26, 2023) is the version used for this installation.

Performance Benchmarks

The SysBench 0.9.5 program no longer works well enough to report its results. Blonde Guy has the source code and will fix the program when time permits. Until then, the only report will be CPU power from PassMark Software.

CPU: Intel(R) Core(TM) i7-6700 CPU @ 3.40GHz
CPU Mark: 8090

PCI devices

There are 11 PCI devices found by the PCI 1.04vkA program.

PCI IDDescription
8086:191FBridge PCI to HOST
8086:1912Display VGA
8086:A12FSerial USB (UHCI), programming interface 30
8086:A13ASimple Communication Other
8086:A13DSimple Communication Serial - 16550
8086:A102Storage Serial ATA (AHCI 1.0)
8086:A114Bridge PCI to PCI
8086:A146Bridge PCI to ISA
8086:A121Memory Other
8086:A170Multimedia Unknown!
8086:A123Serial SMBus Controller
8086:15B7Network Ethernet
197B:2368Storage IDE (ATA)


Preloaded Software

Each Blonde Guy ArcaOS preloaded computer comes with a standard load of software. This page lists what is in the current pre-load. This list is updated over time to incorporate new essential OS/2 software as well as to keep up to date versions of existing software. When you receive your ArcaOS preloaded computer, you will have Blonde Guy's best installation of the latest OS/2 software.

Recovery DVD

The recovery DVD supplied is a bootable ArcaOS DVD with a backup of the hard drive as delivered. You can boot the machine from DVD, and perform maintenance functions. The maintenance folder is available on the recovery DVD. The factory backup is stored in the \Factory directory. The backups are simple zip files. You can use 7z or unzip to extract some or all of the files in a backup.

Build Notes

This section documents what I did to get this computer to work under ArcaOS. It is intended to show what goes into this computer, and also as a guide to the user who wants to build it himself.

BIOS changes

I upgraded the BIOS to BIOS Version FWKTBFA, Date: 06/23/2022; BIOS Revision: 1.191; Firmware: 1.21

BIOS settings

  • Config->CPU->Intel (R) Hyper-Threading Technology = Disabled. (ArcaOS kernel issue left over from OS/2)
  • Startup->UEFI/Legacy Boot = Both (need both to boot BIOS update, otherwise Legacy Only is fine.)
  • Startup->UEFI/Legacy Boot - CSM Support = Yes

For traditional BIOS operation, use the following setting.

  • Startup->UEFI/Legacy Boot - UEFI/Legacy Boot Priority = Legacy First

For UEFI operation, use the following seting.

  • Startup->UEFI/Legacy Boot - UEFI/Legacy Boot Priority = UEFI

ArcaOS Installation

When ArcaOS is installed on a system utilizing UEFI, it may be configured to boot from an MBR disk (primary or logical partition) or from a GPT disk. In the GPT partitioning scheme, there are no concepts of primary or logical partitions. Instead, the ArcaOS emulation layer presents each GPT partition as a single MBR disk with a single drive letter and partition on it.

Because each partition is presented to OS/2 as a single MBR disk, OS/2 disk conventions are no longer a limitation for multiboot systems.

If I have fixed the disk using DiskUtility or other procedure, then I run Disk Utility again. If it says "No problems found.", then I proceed to lay out the disk paritioning that I want using "Manage Volumes (Graphical)."

Once volumes are laid out, I can proceed to install ArcaOS, or use the Blonde Guy Recovery DVD to restore a backed up ArcaOS installation.

Driver Notes

Beginning with the version 12.07 USB drivers, USB 3.0 is working well for mouse and keyboard, even through my KVM. USB sticks now mount successfully. USB sticks can be supported even without an optional USB 2.0 add-in card.

The Disk driver is OS2AHCI with native command queueing enabled. UniAud works.


In BIOS mode, DOS Full-Screen works. Alt-Home from a DOS Full-Screen then allows a DOS Window to work. In UEFI mode, DOS Window and DOS Full-Screen both work.



Magnesium Front


Magnesium Rear

Interior shot with tool-free drive bays.

Magnesium Interior

Expansion slots

Magnesium Slots

Icy Dock 2

This dock holds one SATA 3.5 inch drive and two SATA 2.5 inch drives. It is NOT a hot swap unit. The computer must be powered off to swap drives.

Magnesium Slots