Seems that the Samsung 840 Evo is notorious for performance degradation. : r/buildapc
Samsung 840 EVO SSD review - SSD Performance AS SSD Benchmark
Samsung 850 EVO vs. 840 EVO - Is It Worth The Upgrade? - YouTube
Amazon.com: New A+ Samsung SSD HDD 840 PRO 2.5" 7mm 128GB MZ-7PD128BW MZ7PD128HCFV-1BW00 0Z000 SATA 3.0 6.0Gb/s MLC Hard Disk Solid State Drive Laptop : Electronics
Samsung SSD 840 Pro Review - StorageReview.com
Amazon.com: Samsung Electronics 840 Pro Series 2.5-Inch Solid State Drive, 256GB : Electronics
Samsung 840 EVO SSD review - SSD Performance Crystal DiskMark
The Samsung SSD 840 - Samsung SSD 840 (250GB) Review
Samsung SSD 840 Pro (256GB) Review
Samsung 840 Pro Review (256GB) | Ubergizmo
SAMSUNG 840 EVO SSD 500GB MZ-7TE500BW 2.5" SATA III TLC Internal Solid State Drive - Newegg.com
Samsung 840 Pro Review (256GB) | Ubergizmo
Samsung 840 PRO 256GB for sale online | eBay
256GB SAMSUNG 840 Pro Series 2.5" SATA III SSD - Newegg.com