It depends on your specific model of Syno, but many backplanes are Molex-powered and also do not provide power on the 3.3v pin to the drive, thus avoiding the PWDIS issue.

Provide it with conditioned air for intake, but in the cooling season route the exhaust to your furnace’s air return, to contribute toward heating the house.

• $12 ASR-7805 (2x8643 SAS2), config toggle for HBA
• $17 Inspur 3008 (2x8643 SAS3), flashable to IT firmware

Also Aruba S2500, though recently ICX6450 have been cheaper. Both come in either 24 or 48 port flavors, with or without PoE.

Juniper EX4200 has the nice feature that even the non-PoE models support 8 ports of PoE. A bit louder than the above two, though.