Speed dropped to half after switching from SATA 2 to SATA 3.
Speed dropped to half after switching from SATA 2 to SATA 3.
I just switched my motherboard from Gigabyte to ASUS B150M Pro Gaming. My old board lacked SATA 3, but this one only has SATA 3, yet my write speed dropped significantly. I also have a Seagate Baracuda Black 240 GB SSD connected via SATA 3 in SATA 2.
Install the chipset drivers first, then restart the motherboard; it should change. If they’re already set, just restart the PC and check its status.
From what I observe, your initial test used a completely empty storage, whereas the current setup is nearly 90% utilized. SSDs tend to slow down when they reach capacity, so for an accurate comparison you’d need to run the same test on SATA2 with identical data volume.
I usually reinstall, but the slowdown is probably due to the drive being almost full. If you reinstall and then fill it up again, it won’t fix the problem. The best first step would be to clear some space from the disk, verify trim is off, and try again. You could also reinstall, confirm the speed is acceptable, then reinstall files (which will reduce speed further if you get near 90%).