If the board is only 3 weeks old then I suggest you ask for a replacement under warranty.
These driver chips are designed to be cooled through the PCB, so all-in-one boards usually cool them much better than stepsticks do, because a stepstick doesn't have enough PCB area. Stick on heatsinks are ineffective because the plastic top of the chip is a poor heat conductor. If the chips get hot then I suggest you either turn the current down, or use a fan to blow air from the edge of the PCB so that air flows over both sides. If the electronics is mounted horizontally in a confined space with little convection, such as under the bed of a delta, then it is wise to use a fan anyway
The driver chips on all-in-one boards are usually very reliable, much more reliable than stepsticks according to a company I know that sells both. But you need to guard against bad connections in the motor cables, because an intermittent connection can damage them.
These driver chips are designed to be cooled through the PCB, so all-in-one boards usually cool them much better than stepsticks do, because a stepstick doesn't have enough PCB area. Stick on heatsinks are ineffective because the plastic top of the chip is a poor heat conductor. If the chips get hot then I suggest you either turn the current down, or use a fan to blow air from the edge of the PCB so that air flows over both sides. If the electronics is mounted horizontally in a confined space with little convection, such as under the bed of a delta, then it is wise to use a fan anyway
The driver chips on all-in-one boards are usually very reliable, much more reliable than stepsticks according to a company I know that sells both. But you need to guard against bad connections in the motor cables, because an intermittent connection can damage them.