There can be no doubt that the FastTrak S150 SX4 from Promise is the most impressive-looking component. In addition to the company's own controller chip, the board contains four bridge chips for controlling the SATA hard drives. This tells us that the Promise PDC20621 controller is based on an Ultra ATA model.
The most unusual feature is the SDRAM slot, which has to be populated before use. The SX4 uses the entire memory as cache and supports up to 256 MB. Memory with or without ECC is suitable. But be forewarned: no SDRAM-DIMM is supplied with the card. Just make sure you have a suitable stick of memory when you buy this card.
The SX4 achieved good results in the reading and file server benchmarks but trailed somewhat in the writing and Web server benchmarks. Nevertheless, the data transfer rates were better than the others by a considerable margin. The Promise XOR processor appears to be a very efficient device.
Promise supports all Windows operating systems as well as Red Hat and Suse Linux. There is still no sign of the driver promised for FreeBSD.