I recently purchased a Samsung 830 256GB drive to use as my boot disk. It seems to be performing ok but benchmarking with AS SSD Benchmark has shown problems. Basically my 4K-64Thrd read speeds are only ~25MB/s when most people with this drive are reporting 10x that number. Here's a screenshot
Is your motherboard SATA 2 or SATA 3 compatible?. I found out AFTER I installed the same SSD drive that my Rampage Extreme II is only SATA 2 so although the SSD works it is not as fast is it could be. Still faster then my old Raptor HDD for windows boot up and stuff though.
I tested a crucial M4 and it also was very slow in the 4K-64Thrd speeds, same as the samsung drive. At this point I'm thinking it's something to do with my motherboard. I'm going to install windows on a spare ssd in ahci mode instead of raid and see if that changes it. If not I guess I may have a bad MB.
I unplugged all drives except the crucial M4, then set my SATA configuration to AHCI. I then did a full wipe and installed/updated windows. Then I ran the AS SSD benchmark on it. Lo and behold, the 4K-64Thrd speeds looked fine. It seems my motherboard will have low 4K-64Thrd speeds as long as the sata configuration is set to RAID. I don't know if this by design or a problem with my board.