They look fine. Hard drives have more issues with random read/write operations and the 840's MLC(with 3 bits per cell) is not the fastest at righting data, but as you can see, quite good at reading back data.
Just ensure that you have the latest SATA drivers and are in AHCI mode you should have no issues.
This is seagates new drives(cheap with a lower warranty, but still fast for a hard drive.).
And here are some other "drives".