PCB Design and Functionality

In our recent Asus P6T mainboard review we mentioned that every mainboard usually has a distinguishing feature. The funny thing is that Asus M4A78T-E seems to have no unique features: it is a good board, with pretty standard features and functionality. It is, in fact, also good. Most importantly, there are no evident drawbacks.

Asus M4A78T-E mainboard uses 8-phase processor voltage regulator circuitry that as always consist of very high-quality components. There is an individual phase for powering the integrated memory controller and HyperTransport bus. The power connectors are located in pretty common and therefore convenient spots. The only thing that surprised us was the 4-pin ATX12V connector instead of the 8-pin one although the board is claimed to support up to 140W CPUs. There is no formal connection between the processor power consumption and the number of pins in the ATX12V power connector, however, there is normally an 8-pin connector in this case.

Socket AM3 supports all CPUs designed in this form-factor. At this time AMD offers the following CPUs for Socket AM3: AMD Phenom II X4 and AMD Phenom II X3. However, Asus claims that this board will also support AMD Athlon X4, Athlon X3 and Athlon X2 CPUs, when (and if) they come out. Just in case, let me remind you that Socket AM3 processors have a universal memory controller that supports DDR3 as well as DDR2 SDRAM. Therefore, you can also install a CPU like that into a Socket AM2+ mainboard, but not the other way around. Asus M4A78T-E mainboard is equipped with four DDR3 DIMM slots that support up to 16GB of RAM total. In the nominal CPU mode the memory may function at 1066, 1333 or 1600MHz frequency.

The processor voltage regulator transistors and the chipset North Bridge are covered with relatively large heatsinks with sophisticatedly twisted fins. The chipset South Bridge heatsink is pretty nominal.

Asus M4A78T-E mainboard uses AMD 790GX North Bridge with ATI Radeon HD 3300 graphics core. As for the video memory, up to 512MB of RAM can be used for that purpose. Besides, there are also 128MB of memory on this board that have been assigned to the graphics subsystem via SidePort Memory technology.

When we look at the bottom part of the board, we can notice a COM connector that has been placed unusually high, right next to the chipset North Bridge heatsink. The graphics card slots have been moved a little farther from one another to allow easy use of graphics accelerators with massive cooling systems. If there is only one graphics card installed, it will work at full PCI Express 2.0 x16 speed. With two graphics cards used individually or together as an ATI CrossFireX configuration the slots will switch to x8 mode. The integrated graphics core can also be used together with a discrete graphics card due to ATI Hybrid CrossFireX support.

SB750 South Bridge delivers two PATA channels and six Serial ATA ports supporting RAID 0, 1, 0+1 and 5. Asus M4A78T-E is equipped with five actual SATA ports with the sixth laid out as an eSATA on the back panel. There are also 6 USB 2.0 ports out of the 12 supported by the South Bridge. The remaining six USB 2.0 ports are tied up to three pin-connectors along the lower edge of the PCB. There is an IEEE 1394 port next to them, which is implemented through VIA VT6315N controller. The second IEEE 1394 port provided through this controller is on the back panel. Interestingly enough, the eight-channel sound is implemented through another VIA controller – the VT1708S. I didn’t even known until today that VIA makes audio codecs, too. I have never seen them on mainboards until today.

We didn’t mention the PS/2 keyboard connector, six analogue audio-jacks and digital optical S/PDIF that are also on the connector panel of the board. Moreover, the integrated graphics core provides support for D-Sub, DVI and HDMI, while the Gigabit Atheros L1E controller delivers network RJ45 port.

The components layout scheme from the user’s manual will provide a better idea of Asus M4A78T-E design peculiarities:

We are going to wind up this part of our review with the detailed technical specifications of the Asus M4A78T-E mainboard taken from the manufacturer official web-site: