To me it is the "around 1.7 Tb" placement that seems the most "queer", I cannot imagine which particular (from a pure mathematical standpoint) limit it can come from.
The "around 2 or 2.2 Tb" limit in the MBR architecture is due to the combination of the 32 bit fields for "Sectors before" and "Number of sectors" in the partition table with the "standard" 512 bytes/sector.
That is (4294967296-1)*512=2,199,023,255,040 bytes.
Even on GPT the bootsector data may well have a similar limitation, on NTFS while there is "enough space" for a 64 bit address for "Sectors before" it is entirely possible that only 32 bit are considered in some non-MS code.
If we take into consideration clusters (that on NTFS are usually 8 x 512 bytes sector) the 1.7 Tb is roughly 1.7*1,024^4/(8*512)=456,340,275 which is bigger than 2^28=268,435,456 but less than 2^29=536,870,912.
I don't think that the issue is due to the interface (SAS) of the disk or to the BIOS (though it is still possible) and surely we cannot ask you to buy another disk drive if you don't actually need it, but if and when you will find yourself in the need of getting another hard disk for backup it would be interestingif you could do some experiments with partitioning/formatting it.
About capacity the manufcturer uses "false" or "metric" prefixes, 1 Terabyte for them is 1000^4=1,000,000,000,000 bytes, all operating systems and progerammers normally use "real" or "binary" prefixes 1 Terabyte for them is 1024^4=1,099,511,627,776 since there was confusion with this the "real" Terabyte has been (correctly from a "unification of prefixes" standpoing but "wrongly" as it caused even more confusion) renamed to Tebibyte:
abbreviated (officially) Tib.
A number of people (myself included) will always use "real" or "binary" units and use the more common Tb (or Kb, Mb, Gb, etc. abbreviations), because we were raised and learned computing using them and as well MS always use them that way (if you prefer non SI/IEC compliant).
Your disk is around 4 Tb=4,000,000,000,000 bytes that correspond to 4,000,000,000,000/1,099,511,627,776=3.6379 Tib