Sources seem hard to come by regarding Windows’ behavior regarding TRIM and formatting.
This now removed blog entry on msdn.com states that since Windows 7, TRIM is sent to the SSD when formatting to NTFS (emphasis mine):
In Windows 7, if an SSD reports it supports the Trim attribute of the ATA protocol’s Data Set Management command, the NTFS file system will request the ATA driver to issue the new operation to the device when files are deleted and it is safe to erase the SSD pages backing the files.
The Trim operation is fully integrated with partition- and volume-level commands like Format and Delete, with file system commands relating to truncate and compression, and with the System Restore (aka Volume Snapshot) feature.
Wikipedia is undecided on whether TRIM is even supported for FAT on Windows:
Sources disagree on whether TRIM support exists for other filesystems (than NTFS).
Is there any information on whether Windows 10 issues TRIM when formatting with FAT?