RE: T7500 sas ports question can i use them for sata drive storage?
The drives will work the same as if you connected them to SATA ports. In terms of drive letters, that depends on what's on the drives and whether they're running through a RAID controller. For simplicity, I'll assume that there's either no RAID controller, or there is and you're just not going to put them into a RAID array.
Drive letters are assigned to partitions, not drives. So for each drive you install, if it's not initialized (i.e. it has no partitions on it), you would have to initialize it first, then you would create one or more partitions on the drive, and a drive letter would then be assigned to each partition. Or you might find that the drive already has one or more partitions set up, in which case each partition would automatically be assigned a drive letter. You would then have to decide whether you wish to keep the existing partition layout and file system (FAT32 vs NTFS, for example) or whether you instead want to erase the drive and set it up from scratch. The Disk Management utility in Windows would help you do all of this.