https://www.techpowerup.com/252010/fsp-introduces-modular-flex-atx-psu-with-mechanical-design
 
The needs for Flex ATX specification power supplies are also increasing. FSP has great advantages in the Flex ATX power supply product markets; not only does it have the most complete Flex ATX products (with over 30 models in this form factor), most of these products also complies with the 80PLUS requirement, offering a variety of efficiency ratings ranging from bronze to platinum.
 
I like the design of these power supplies because they allow you to quick disconnect cabling for faster troubleshooting. 
 
FSP Flex ATX Modular Power Supply Features:

• Fully modular design
• Cable customization
• Special mounting hole and auxiliary bracket design
• Complies with the latest Intel Flex ATX V1.22 specifications
• Complies with UL/EN/IEC 62368-1 and 60950 International safety standards
• Power density is improved over the general Flex ATX by 20%
• Special airflow direction to extend the service life of the fan (it draws external air into the power supply and then takes hot air out)
• Uses high-quality capacitors made in Japan
• Low noise design:
  o Unique fan noise shielding design
  o Smart fan control system
  o Durable and quiet 40 mm ball bearing fan
• 220W and 250W meet 80 PLUS bronze-certified efficiency standards
• Single 12V cable output design
• Multiple protection mechanism: OVP, UVP, OCP, SCP, OPP