Chipset letters : X Z H Q B > Meaning of the letter in the model name of a computer motherboard

X , Z

Has the latest features, fully support CPU overclocking, and must be used with a "K" (unlocked) processor. 

High end motherboards that give the best performance for gamers and productivity.

They support completely different CPUs, X is for LGA 2011, and Z is for LGA 1050/1055. 

A consumer with an i5-4690K can choose between a Z97, H97, B85, or Q87 motherboard, but not a X99.

H

Slightly trimmed down version of the Z, that is a good option if you don't want to pay the premium cost.

Q

Model between the H and Z. It's for high-end business or low-end workstations, and it's the only one where Intel officially supports VT-d, but not made for audio.

B

Is for "business", a cheaper motherboard for office, school or home.

Specifications

X

- Fully support CPU overclocking natively.
- higher power delivery.
- extra water pump headers.
- allow tweak of pump speed in BIOS and OS.
- better audio with sepparations for electrical interferance.
- solid capacitors.
- reinforced PCIe slots.
- protecting metal back plate.
- rgb header.
- nvme m.2 slots.

Z

- Fully support CPU overclocking natively.
- higher power delivery.
- extra water pump headers.
- allow tweak of pump speed in BIOS and OS.
- better audio with sepparations for electrical interferance.
- solid capacitors.
- reinforced PCIe slots.
- protecting metal back plate.
- rgb header.
- nvme m.2 slots.