Just ran a benchmark on my SSD, and something seems seriously wrong here.

Your MB has two types of SATAIII ports, one set are intel (red) and other set are ASMedia that is also red color too. You may be connect the SSD into the ASMedia sata port. Check your MB manual, reconnect the SSD to the intel SATAIII port if you don't use the intel one.

The difference between the evo and the pro are almost non existant. Any benchmark you run on the evo with rapid will give you pure boost made for benchmark scores. example, I run on my 1tb evo which is os/boot drive with rapid, I get between 700-999 mbps read, and around 600-700 write. But when I transfer a file off that drive and onto my raid cage (8hhd in raid, theoretical speeds of 600-800mbps), I average around 300mbps.

As far as pro vs evo. The evo needs this rapid mode to gain the speeds the pro 'just offers'. Which makes it a great cheap os solution vs the pro. But the pro also has a higher endourance vs the evo. So whichever drive you write to more often make that the pro. Another huge thing is, the larger the drive, the longer and faster it will stay.

SSD are designed to write from first to the last block, then start that process over again. Once you write into a block, and then delete it, the controller of the ssd marks it as deleted, but doesn't actualy delete it. (this saves on life cycles). Then when you span from first to last byte and start over again, the controller knows which bytes are 'empty' (marked as deleted) and then writes into those. This is much slower than writing into an empty block.

Another pro vs evo concept. The pro uses 2 bytes per block, whereas the evo uses 3 bytes per block. Which is why the pro is rated to last longer. So, theoretically, (and proven in a few tests), the pro continues to offer better speeds after its been written on over and over, since theres less information being read/written in each individual block.

So, my 2 cents, keep the pro as the boot. Honestly for the evo, id take it out and replace it with a 1tb 7200rpm hhd. That way you have massive space, and endourance if you want to go write crazy. Then for like $20 buy an external 2.5" hhd encolure that's usb3.0, stick your evo in there. Then when you want to save or need the 300mbps vs 100mbps, plug in your evo and your good to go. I just started getting into external ssd storage, and its phnenominal. I have 2 512gb crucial m550 msata on a 2.5" sata controller connected in raid, in a external usb3.0 enclosure, and get read/write speeds 600-800mbps. With full terabyte of storage. Wickedness! And for the price of usb 3.0 flash pen/stick drives, you get a 256gb for $100-130, or you can buy a 256gb ssd for $110-120 and an enclosure for $20, same price but 5x the speeds for the same capacity. But don't use Samsung evo drives for massive data write storage, as theyre not meant for it, plus theyre speeds without rapid are around 300mbps. I use crucial 550/500's. Crucial 550's are close to the pro in terms of endourance and speeds, but the 500 are dirt cheap, write speeds are decent.

OH, edit about the rapid not being enabled. Rapid can only be enabled on evo drives when theyre being used as a os/boot drive. What rapid does, is it takes unused ram and uses that as a sort of buffer for cache. So by using unused ram, it has access to the outstanding speeds that ram has to offer. It also is very good about only using unused ram. If you start to open up programs/pages and gaming and such and start to use your ram, the rapid then gives up that ram you need.