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6 guaranteed-fit options
Guaranteed-fit promise
Every kit is matched to your machine's slots and checked against its published specs before we list it.
DDR2 · SO-DIMM · up to 800 MT/s · Non-ECC · Unbuffered
2×512MB = 1GB
Verified fit for your systemNot stocked right now. It's verified to fit — get an email the moment it's back.
Every option here is verified to fit this system. Muted means it fits too — we just don't stock it right now. Pick one to switch.
Software for your upgrade — matched to your Sony VAIO CS Series VGN-CS21Z/Q.
Checks the drivers on your Sony VAIO CS Series VGN-CS21Z/Q, installs the safe updates Windows offers, guides the rest to the official download — and confirms exactly which of the upgrades above your machine has room for.
Sony VAIO CS Series VGN-CS21Z/Q takes DDR2 SODIMM memory, 2 slots, up to 4 GB. Every option above matches those requirements, so it typically installs and runs without any firmware change.
“Spec match” means the module matches your system’s published specifications; it isn’t yet confirmed against a manufacturer tool.
Specifications reported for the Sony VAIO CS Series VGN-CS21Z/Q.
Good to know
We've already verified which memory and storage upgrades fit this exact machine — they're just not in stock at the moment. Leave your email and we'll tell you the moment any of them is available again. Guaranteed fit, no wrong parts.