What are they?? SATA for what type of drive?

[YooperComp]

I’m running a

HP Z420 v1

32Gb of ram 

Xeon E-5 .1603 0 @ 2.8 GHz

2 TB SSD main drive

3TB HDD Storage

500GB HDD  for a redundant back up some day here soon when I figure out how that’s for the software side go’s

any advice is welcome and please forgive me if I’m in the wrong group

Question I have is they are SCU at 3 GB/s but what is an SCU drive there’s four of them there are number 17 on the picture and I have no idea what they’re for they don’t work on my SSD or the regular hard drive HDD.. I’m sure it’s obvious I’m just getting to OLD but love tech..

Thanks again

Jim

[YooperComp]

Nevermind all i found my answer to what they are either dead ports or more SATA ports did some reading on this communitys pages and found out im missing a SAS riser i looked where a riser is suppose to be it even says SAS OPT 

Thanks again 

JIM