2- or 3-Phase Power Supply?
The A7M266 is using a standard power supply; the EP-8K7A has a 2-phase supply with 4 MOSFETs, and the GA-7DXR a 3-phase-power supply with 6 MOSFETs. Why that? We have to admit that our knowledge in the field is limited. After some research we came to this: MOSFET stands for "Metal Oxide Semiconductor Field Effect Transistor". Sounds impressive! MOSFETs insulate with a layer of silicon dioxide the metal gate from the semiconductor current channel. They have extremely high input impedance and therefore require almost no driving power. MOSFETs are used for low-voltage regulation, because they drop less voltage than other transistors do. MOSFETs are therefore perfect for regulate the CPU power supply. A 3-phase power supply is splitting the current among 6 MOSFETs. A 2-phase supply is splitting the current among only 4 MOSFETs. Consequently a 2-phase circuitry is running hotter. To offset this, the EP-8K7A has additional heat sinks on the front side PCB. In theory a 3-phase supply as the GA-7DXR has (and Epox is using on other boards like the EP-8KTA3) is better, while running cooler. The 6 MOSFETS on the Gigabyte 7DXR never got hotter than 36C whereas the EP-8K7A 4 MOSFETs on the front-side PCB were running up to 50C despite the heatsinks. When provided with sufficient cooling, there shouldn't be any problem. A 2-phase solution is naturally cheaper than a 3-phase solution. And it looks again as if Gigabyte has opted for a quality approach. In our comparison, however, we did not find any "issue" which could have been attributed to the different circuitry we found on these 3 boards. We also did not experience the cold boot problems with the EP-8K7A reported in this review on LostCircuits.

Epox 8K7A - the four MOSFETs on the PCB back side

Gigabyte 7DXR - the six MOSFETs on the PCB front side

Temperature on the GA-7DXR MOSFETs under full load, ambient at 25C

It has to be noted, that a standard circuitry, a 2-phase or a 3-phase power supply have nothing to do with the compatibility for the upcoming Athlon 4 (Palamino). The Athlon 4 will anyway run at lower voltage and dissipate less heat. Gigabyte has already published a list with Palamino compatible boards: it seems there are many older boards on the list with a standard power supply such as the A7M266 has.