Usually I focus on the latest hardware available, but this month I break with tradition to show how 10-year-old hardware can be brought back into service easily and effectively – not to mention in a really cost-effective way.

Return to ThinkPad Island

Upgrading a desktop-class system would be in no way remarkable, because the venerable ATX family of standards [1] enables replacing a system's board entirely, if needed, retrofitting a wholly new system in place when an upgrade warrants it. Upgrading a laptop sets a higher bar and has become essentially impossible in the current era of ultrabook-class machines with soldered-in components. However, this feat can be achieved with 10-year-old hardware, with surprisingly practical results. Choosing the right equipment is critical, because only some laptops are upgradable, and even fewer models are worth upgrading for use today.

I start with a stock ThinkPad T420 [2] made in 2011 by Lenovo (Figure 1). Almost five pounds (2.24kg) heavy, the best T420 revision sports a 1600x900 screen that will not make your eyes want, even today. Unfortunately, my unit came with the lesser 1366x768 screen option, but it is still perfectly suitable for its target application at the lab, which is to render sliced 3D models for printing during the day and drive a telescope's CCD camera at night. Digging around on eBay, I was able to find a stock unit in nearly perfect condition for $185, still comparing nicely to today's low-end netbook format devices if one disregards its heft and bulk.

Figure 1: The object of this project – a ThinkPad T420, circa 2011.

Shopping Spree

With a system in hand, I start with the upgrades. The most obvious target is the paltry 4GB of installed RAM – perfectly adequate to run Linux even a decade later; however, because my intended purpose is to run recent, custom OEM software as supplied by hardware vendors, I sadly need to step up to the much higher requirements of Windows 10. Amazon supplied a 16GB upgrade for a mere $62, including shipping [3], for two 8GB DDR3 RAM 204-pin SODIMMs (PC10600 or PC3 1,333MHz). This unit came equipped with its maximum storage option: a SATA 500GB drive running at 7,200rpm – certainly impressive back then, but not so much today. The mSATA slot of the T420 can be used for more than WLAN options, and the biggest problem thus becomes finding a seller of mSATA hardware, as opposed to the newer M2 format that has since replaced it. I turned again to eBay, where an excellent 250GB Samsung 850 EVO solid-state drive (SSD) [4] was on sale for just $39.95 (Figure 2). This being solid-state storage, I acquired a new part, because previous use makes a material difference to its longevity.

Figure 2: Procuring upgrade parts on eBay – in this case, a 250GB Samsung 850 SSD.

My final, ambitious upgrade targets the processor. This system's CPU is socketed, and the original two-core i5-2520M [5] can use some additional brawn to offload the Windows 10 task threads. The T420 is fully 64-bit, and the BIOS supports replacing the i5 with a higher class i7-2670QM [6] ($58 on eBay, a used system pull). The trade upgrades the system to four cores and doubles the cache size (from 3 to 6MB), in exchange for a small drop in baseline clock speed – 2.3 to 2.2GHz (peak drops from 3.2 to 3.1GHz).

Major Surgery

Legend has it that no one has ever opened a ThinkPad without, in the process, breaking one of the tabs of the casing. Back then, other members of Canonical's leadership team used to seek me out for emergency laptop repairs during strategy sprints hosted in remote locations. Having opened many ThinkPads over the years, I can confirm it is never easy, but it becomes decidedly more difficult if you do not take your time: I encourage you to proceed slowly.

Opening the laptop's bottom port gives access to the mSATA slot and one of the RAM SODIMMs (Figure 3). These are the easiest steps of the upgrade, but do take care to maintain the insulation around the antenna terminals, lest they wander and short other components. Once you remove the single keyboard restraining screw, you can install the second SODIMM in a slot located under the keyboard (Figure 4).

Figure 3: Completing installation of one RAM stick and the SSD in the bottom case port.

Figure 4: Removing the keyboard reveals the second RAM location (under the plastic sheet) and the CPU assembly.

The CPU assembly is now visible, but opening the heat sink requires removing the top bezel of the laptop first, and this is best done by following the steps taken by someone else as a guide. A few YouTube videos help here [7] [8]; just follow along to identify what screws need removing. Once the bezel is lifted off the case (Figure 5), the heat sink, heat pipes, and fan assembly must be removed as a single unit (Figure 6), enabling swapping of the Intel Core CPU (Figure 7). Do not forget to reattach the keyboard and touchpad connectors during reassembly.

Figure 5: Lifting the top bezel is the most complex part of the operation. A spudger will be a great help. If an accident happens, a replacement bezel can be found on eBay.

Figure 6: The CPU assembly. Note the numbered sequence ordering the screw-tightening operations.

Figure 7: The old CPU alongside the new. In this case, die sizing reflects the number of cores.

A refurbished system will usually come with a preloaded copy of Windows; this upgrade requires relocating the operating system to another drive, which is best done with third-party software. I used Partition Master [9] to take care of the process, because Windows does not include tooling for this purpose.

If you dare to take your chances and open up a laptop, you can build a remarkable, compact, single-task device with very limited expense. The resulting system as described here cost $345, including $160 spent in upgrades – quite competitive for a quad-core mobile unit with 16GB of RAM. The most remarkable change is in boot time, which has gone from over a minute (with tasks still running) to under 10 seconds, with a very responsive, user ready system. I have even more ambitious plans for this system that involve outfitting the modular UltraBay slot with a 3D-printed custom drive …, but that will have to wait for another column – I am out of space for this month!