Bought this Old late 2013 16gb a1398 15inch MacBook Pro. Had Yosemite OS installed and only 32 battery cycles. Hardly used it seems. I know people more excited about the new 2020
The Super MacBook Pro Upgrade (1TB RAID SSD Upgrade + RAM Upgrade 2013) - YouTube
Amazon.com: 2.6 GHz 16GB RAM Logic Board 820-3332-A for Apple MacBook Pro 15" Retina A1398 2012 Early 2013 : Electronics
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Apple MacBook Pro A1398 15.4" 16GB 512GB Intel Core i7-4870HQ X4 2.5GH – Device Refresh
Upgrading Ram in a Macbook Pro 13" | How to Upgrade Ram on 13" Macbook Pro - YouTube