|SCSI and SATA are totally different interfaces. Just as IDE (PATA) and SATA are different. Additionally there are many different "flavors" of SCSI.|
What riider was pointing out is that the servers in question may not (probably not) have any connections on the motherboard for SATA hard drives. If there are no connections you would need to purchase an add in SCSI card. If you wanted server grade SATA with RAID capabilities the card itself can get expensive. Not to mention hard drive prices are currently very inflated due to a major producer currently being out of service.
The main differences in true server type units is redundancy and quality.
The line between servers and PCs has been getting blurrier for some time.
I am not clear on your purpose in buying the used servers but perhaps you could accomplish the same thing with a consumer/business class machine.
Even if you got the servers for free, by the time you install multiple SATA drives and a controller card you may have many hundreds invested in older/ slower technology.