Serial Vs Parallel Delivery. The main reason for going either parallel or serial is the overall aesthetics. Serial communication is suitable for long distance transmission of data as against parallel communication is suitable for short distance transmission of data.
While parallel port is used to achieve parallel transmission. On other hand parallel transmission is the transmission in which multiple parallel links are used that transmit each bit of data simultaneously. While transmission speed of parallel port is higher than serial port transmission speed.
Serial data transmission sends data bits one after another over a single channel.
The main reason for going either parallel or serial is the overall aesthetics. Parallel data transmission sends multiple data bits at the same time over multiple channels. Just like in the second picture where all water cooling is in the bottom and middle part of the case making the parallel loop a clear winner for aesthetics. A parallel loop can be done much cleaner if you have all liquid cooling components in one area of the case.
