The problem with 840 evo is the slow read bug when you have old data (at least a few weeks old). New one doesn't show this sign. There might be other issues tht caused the slow reads of your 840 evo.

maybe you should tell us more about your machine that the ssd is attached to.
iops (input/output operations per second) is basically a performance indicator for storage (i.e. how often a storage device can perform io tasks). in general, the higher the numbers the better. what makes ssd shines is its iops for random reads and writes of small files (which usually reflects typical computer usage), which is much higher than hdd.

there are many things that can influence iops, but we assume that these results are from the same test environment, using the same measurement tools by all manufacturers. (so, we can use it for reference only, because the numbers vary in different scenarios)

wikipedia has a page about this.

edit: sorry i posted this too slow. wcypierre explained about iops already lol

are you connecting the ssd to the intel sata3 port? from the manual the mobo only has 1x intel sata3 port.

by the way what's the OS?

yeah i guess you are connecting to a sata3 port, too. however is that port an intel sata3 port?

yes you do. just refer to the mobo manual for the right location of the intel port.

i suspect you have plugged the ssd into a non-intel sata3 port, hence the slower speed.
yes. it will be your storage.

what do you wanna achieve? a dual-boot? if you wanna have a dual-boot system, it's better to review the tutorials available online (google them. there are a lot of them). if you don't need that, it's better to unplug the hdd, install windows with only ssd, then reconnect the hdd to the system after that. better yet, just clean up the os/system/recovery partitions on the hdd first to avoid boot issues if you don't know how to handle it.

Lu manyak kaya eh can spend 1k on 500 gig i poor lass can only afford 250 gig dang

Msi z97
8gb ram
I7 4790K with 4 ghz
770 limited 4 gig classified edition by evga