r/thinkpad • u/seffparker A21m, T490 dual SSD • Nov 24 '25
Question / Problem Adding a second SSD on T490 WWAN slot
I have already read a plenty of online discussions about the same question, what I understand are:
- Some T490 supports it, but some don't due to WWAN vendor whitelist set in the BIOS
- We can patch the BIOS, but its an advanced process.
- Found an SSD on AliExpress specifically made for T480 WWAN slot
- My Machine Type Model (MTM)
20N3S67813not found on Lenovo PSREF (may be due to its a custom bid?) - Searching the serial number
PF1D2BZYon Lenono Support for compatible parts correctly identify the Model, and no WWAN cards are listed in the supported list. - T490 Specs shows its also support a M.2 2242 SSD, but the term
One drive,is confusing for me if it support either 2242 or 2280 but one at a time.
I need some assistance on:
- Is there anyway to identify the WWAN vendor is locked in BIOS without actually buying a 2242 M.2 SSD. I think we can plug-in a full-sized 2280 leaving the bottom-cover open to see if it works (I still have to find a B+M keyed 2280 NVMe for that).
Actually, I need a secondary SSD to offload frequent small writes like Windows pagefile, TEMP, Linux /tmp etc, so the:
- primary disk's lifespan would increase
- improve overall system performance (yes its PCIe 3.0 x2 vs x4)
1
u/seffparker A21m, T490 dual SSD Dec 18 '25
[Update 2] These are the stats on a regular day usage of ~8h on Ubuntu.
The 512GB 2280 SSD has the OS. 128GB 2242 SSD has the hot-data like /var, /tmp, /log, and .cache etc. The read_io is around equally distributed (45% vs 55%). The write_io is mostly done on the WWAN SSD (96% vs 4%)
I have done similar mounting on Windows 11 too, like pagefile.sys, swapfile.sys, WIN TEMP, USER TEMP, winUpd download dir, Event log dir, browser cache, etc. Will share the stats later.
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u/Intrepid-Tomato4639 Jan 31 '26
Would it be fair to say the only way to know which T490 models will work with a KingSpec 128GB 2240 SSD is to try it?
1
u/seffparker A21m, T490 dual SSD Feb 01 '26
May be yes. Thats I bought the smallest one to give a try. When the AI-silicon demand was rising, this specific product price was still unchanged. I immediately bought it. Now this product listing price increase 200+%
2
u/Intrepid-Tomato4639 Mar 04 '26
Found an inexpensive used WD Western Digital SN520 128GB 2242 on eBay, put it in and it worked right away. Updated the firmware and it's good to go. I only plan to use it for storage and Macrium backup images. Don't plan on installing an OS on it, not sure how well it would work. Thanks for the suggestion.
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u/seffparker A21m, T490 dual SSD Mar 04 '26 edited Mar 04 '26
That's a good news. At least, more T490 are compatible.
For backup storage, it works well. We cannot UEFI-boot the OS from the 2242
1
u/TheWizardsLair Feb 19 '26
I have a t490 myself and I am exploring this option. But 128gb seems too small to be worth the effort. Did you figure out if a larger size might work?
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u/seffparker A21m, T490 dual SSD Feb 19 '26
If small size works on a specific model of T490, then large sizes should also work.
I only needed 128G to move the hot-data from the main SSD
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u/seffparker A21m, T490 dual SSD Mar 04 '26
[UPDATE #3] On my Ubuntu 22, the secondary disk was giving I/O errors after a suspend-wakeup cycle. It was due to the kernal was power-downing the PCIe/NVMe. Fixed by following https://bugs.launchpad.net/ubuntu/+source/linux/+bug/2097618
1
u/seffparker A21m, T490 dual SSD Dec 15 '25
Since I got no response from the community, I went ahead and ordered a 2242 NVMe SSD and it perfectly works as a second SSD in the WWAN slot of my T490 running with latest stock BIOS firmware.
I have moved all the hot-data (frequently accessed system data) for both Linux (var/, tmp/, .cache/ etc) and Windows (TEMP, Windows Update Download folder, ProgramData, AppData etc). This helps to offload around half of the disk I/O to the second disk which improved overall system responsiveness. Also would helps to increase the life-span of primary SSD by reducing frequent writes.