Lenovo ThinkPad T420 upgrades
Released 2011 · on sale
Lenovo ThinkPad T420/T420i (machine types 4236/4237), Sandy Bridge business laptop. CPU is socketed (rPGA988B) and both SO-DIMM slots are user-accessible under the bottom panel - nothing is soldered. Check the exact MTM before buying parts: stock RAM, drives and radios vary widely between CTO/retail configs. A hidden service partition reduces usable space on small SSDs. Memory and CPU figures marked 'official' in the notes are Lenovo validation limits, not hard hardware limits.
Upgrade guide → What fits, step by step, and official documents.
- 2x SO-DIMM DDR3-1333 (204-pin), no soldered RAM: 2 × DDR3 SO-DIMM · up to 16 GB total · 1333 MT/s
- 2.5" SATA (9.5 mm) + mSATA in WWAN mini-card slot: SSD / HDD 2.5" / M.2 2230 / M.2 2280 (SATA / NVMe) · max 9.5 mm thick
- Socket G2 (rPGA988B) - Sandy Bridge only, 35 W: LGA1151 (6th/7th gen) · Ryzen 3000 · max 35 W
Slot map
2x SO-DIMM DDR3-1333 (204-pin), no soldered RAM 2 × DDR3 SO-DIMM · up to 16 GB total · 1333 MT/s
Lenovo officially validates 4 GB modules / 8 GB total; Kingston and community tests confirm 2x 8 GB = 16 GB works, so 8 GB is the real per-slot ceiling. 1600 MHz sticks run downclocked at 1333 MHz. Buy DDR3 1.5 V (or dual-voltage DDR3L); avoid 1.35 V-only sticks. Non-parity unbuffered only. T420i is officially capped at 8 GB.
| $/GB | Price | Capacity | Product | Condition | Store | Link |
|---|---|---|---|---|---|---|
| $1.88 | $15.00 | 8 GB | Crucial 8GB DDR3L-1600 SO-DIMM runs at 1333 MT/s DDR3-1600 CL11 SO-DIMM | Used | eBay US +2 | View deal Amazon Price alert |
| $2.00 | $15.99 | 8 GB | Crucial 8GB DDR3L-1600 SO-DIMM runs at 1333 MT/s DDR3-1600 CL11 SO-DIMM | Refurbished | eBay US | View deal Amazon Price alert |
| $2.49 | $19.95 | 8 GB | Crucial 8GB DDR3L-1600 SO-DIMM runs at 1333 MT/s DDR3-1600 CL11 SO-DIMM | New | eBay US +2 | View deal Amazon Price alert |
2.5" SATA (9.5 mm) + mSATA in WWAN mini-card slot SSD / HDD 2.5" / M.2 2230 / M.2 2280 (SATA / NVMe) · max 9.5 mm thick
Main bay: 9.5 mm HDD or 7 mm SSD (7 mm SSDs may need a bracket/spacer). Ultrabay Enhanced (12.7 mm) takes a second 2.5" drive only with an Ultrabay HDD caddy. mSATA shares the WWAN mini-card slot and is capped at SATA II 3 Gb/s; the SATA link is validated at 3 Gb/s, so don't overspend on fast SATA III SSDs. BIOS whitelists WLAN/WWAN cards. No documented capacity limit.
| $/TB | Price | Capacity | Product | Condition | Store | Link |
|---|---|---|---|---|---|---|
| $16.60 | $8.30 | 500 GB | HGST Travelstar Z7K500 500GB 2.5" 7200 RPM HDD (7 mm) 2.5" HDD · SATA · 7200 rpm · 7 mm | Used | eBay US +2 | View deal Amazon Price alert |
| $19.72 | $9.86 | 500 GB | Seagate Laptop Thin 500GB 2.5" 7200 RPM HDD (7 mm) 2.5" HDD · SATA · 7200 rpm · 7 mm | Used | eBay US +2 | View deal Amazon Price alert |
| $19.99 | $19.99 | 1 TB | Travelstar 5K1000 1 TB 2.5" HDD · SATA · 5400 rpm · 9.5 mm | Used | eBay US +2 | View deal Amazon Price alert |
| $19.99 | $19.99 | 1 TB | MQ01ABD100 1 TB 2.5" SATA HDD (5400 RPM) 2.5" HDD · SATA · 5400 rpm · 9.5 mm | Used | eBay US +2 | View deal Amazon Price alert |
| $20.00 | $10.00 | 500 GB | Toshiba 500GB 2.5" 5400 RPM HDD (7 mm) 2.5" HDD · SATA · 5400 rpm · 7 mm | Used | eBay US +2 | View deal Amazon Price alert |
| $24.00 | $24.00 | 1 TB | MQ04ABF100 1 TB 2.5" HDD · SATA · 5400 rpm · 7 mm | Used | eBay US +2 | View deal Amazon Price alert |
| $24.95 | $24.95 | 1 TB | Travelstar 5K1000 HTS541010A9E662 1 TB 2.5" SATA HDD (5400 RPM) 2.5" HDD · SATA · 5400 rpm · 9.5 mm | Used | eBay US +2 | View deal Amazon Price alert |
| $27.25 | $27.25 | 1 TB | Travelstar 7K1000 1 TB (7200 RPM) 2.5" HDD · SATA · 7200 rpm · 9.5 mm | Used | eBay US +2 | View deal Amazon Price alert |
| $27.99 | $27.99 | 1 TB | Travelstar 7K1000 1 TB (7200 RPM) 2.5" HDD · SATA · 7200 rpm · 9.5 mm | New | eBay US +1 | View deal Amazon Price alert |
| $35.90 | $17.95 | 500 GB | Seagate Laptop Thin 500GB 2.5" 7200 RPM HDD (7 mm) 2.5" HDD · SATA · 7200 rpm · 7 mm | Refurbished | eBay US | View deal Amazon Price alert |
All compatible storage with filters → · Compare prices: NVMe M.2 2280 SSD, NVMe M.2 2230 SSD, 2.5" SATA SSD, 2.5" laptop hard drive
Socket G2 (rPGA988B) - Sandy Bridge only, 35 W LGA1151 (6th/7th gen) · Ryzen 3000 · max 35 W
Socket is Intel Socket G2 / rPGA988B (socketed, not soldered) - it is outside the standard Intel LGA naming list. Only 2nd-gen Core Sandy Bridge is supported: i3-2310M, i5-2410M/2520M/2540M, i7-2620M, all dual-core 35 W. 45 W quad-cores (i7-2630QM/2670QM/2720QM) are an unofficial mod with thermal, noise and BIOS-acceptance risk. Ivy Bridge is unsupported (HM65/QM67 chipset/BIOS).
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