ASUS M4A78T-E 790GX AM3 Motherboard Review

Voltage Regulation

Our voltage regulation testing will focus on the various voltages and the differences encountered between what is selected in the BIOS and what is reported by a digital multi-meter (DMM). We have found five voltage read points on the motherboard so the vCORE, CPU/NB, NB, HT, SB, and vDIMM will be recorded with our DMM. The vCORE and CPU/NB will be read from the underside of the motherboard at the output side of the corresponding inductor. The remaining voltages will be read from points on the top of the motherboard. vDIMM will be read directly from a DIMM slot's VDD pin. The ground point used for all readings will be a screw hole. Here are a few photos showing the various read points used.



Now that we have established where the read points are, let’s have a look at the results. These measurements were taken at stock system speeds and with Cool N' Quiet and C1E disabled in the BIOS. So without further ado, here are our extensive findings:


Taken as a whole, what you see is what you get with the M4A78T-E. It has very good voltage output. There is relatively little variance between what you select in the BIOS and what the board actually outputs. The HT, NB, SB, and DRAM voltages are effectively perfect. It should be noted that when the DRAM voltage is set to AUTO with memory speeds of DDR3-1333 and above, it defaults to a hefty 1.92V, so keep that in mind if you are using the new generation of low voltage DDR3 modules. The critical CPU/NB voltage, which feeds the integrated memory controller, overvolts by approximately 0.3-0.5V once you manually set 1.25V or above. As with the DRAM voltage, when left on AUTO and a memory frequency of DDR3-1333 and above is selected, the CPU/NB defaults to roughly ~1.41V, which is appropriate. While the vCore undervolts by approximately 0.3-0.4V, this is a relatively minimal droop and it won't affect stability nor overclocking. There is no Load-Line Calibration (LLC) feature (yet) for Phenom II processors. Although we would usually take a closer look at the vCORE's characteristics with a one hour OCCT stress test, the current version's of the program does not seem to recognize this motherboard's vCore line.

Temperature Testing

Now it's time to see if the M4A78T-E's simplistic cooling system works as well it as looks. Although this motherboard has a temperature sensor for the northbridge its accuracy seemed slightly suspect to us. Therefore, we relied on our trusty digital thermometer for all temperature measurements. We set the system to its overclocked configuration, and then ran Prime 95 Blend for one hour. In order to test stress the IGP, we subsequently ran a Crysis timedemo on loop for one hour. In both cases, the temperatures were recorded at ten minute intervals throughout the one hour tests and the results averaged out. The ambient temperature was 20°C/68°F


Considering our substantial overclock and liberal use of voltage, we were impressed with these temperature results. Even with its relatively dinky heatsink, having the IGP enabled only increases the northbridge temperatures by a relatively minor 8°C. None of the above components benefited from any direct air cooling, so all these figures essentially represent a worst-case scenario. In a regular case with some half-decent airflow, temperatures should be even lower. As a result, we can definitely state that the M4A78T-E's cooling system is capable of handling all but the most extreme overclocking attempts, and we can also commend AMD for making such cool running chipsets.

Power Consumption

In order to test this system's default power consumption, we enabled both Cool'n'Quiet and C1E in the BIOS, then let the system idle for 1 hour and measured the KW/h power consumption through our UPM EM100 power meter. We repeated the same procedure for 1 hour of Prime 95 Blend load. We then installed the EPU software, set it to maximum energy saving, and repeated the tests. Here are the results:


As you can see, we did not measure any decrease in power consumption when EPU was installed. In both cases, the Phenom II X3 downclocked to 800Mhz (4 x 200Mhz) when idle, so clearly AMD's power savings technologies are doing their functions well. The system with the GeForce GTX 280 idled in the 110W range and reached a peak of 172W when running Prime 95 Blend. The IGP-enabled system idled at a frugal 65W and maxed out at 128W under load, which is quite impressive for modern system.