ASUS P7P55D Deluxe Lynnfield Motherboard Review

Voltage Regulation / Power Consumption

Our voltage regulation testing will focus on the various voltages and the differences encountered between what is selected in the BIOS, what is reported by the PC Probe II utility (when available), and what is measured by a digital multi-meter (DMM). We have found five voltage read points on this motherboard (vCORE, CPU VTT, CPU PLL, PCH, vDIMM), and they will be examined with our trusty DMM. All five voltages were measured from read points on the front of the motherboard. The ground point used for all readings will be a screw hole. Here are a few photos showing the various read points used, which are all conveniently located in the top-right corner of the P7P55D Deluxe.

Voltage Regulation

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 C1E, SpeedStep, Turbo Boost, and Thermal Monitor disabled in the BIOS. Just to clarify, the vCore (LLC) section is the vCore results with Load-Line Calibration enabled. Here are our extensive findings:


What can we say? The P7P55D Deluxe has damn near perfect voltage output, and there is effectively no variance between idle and load states for any of the voltages. Most impressive! The most noteworthy voltage is obviously the vCore, and not only is accurate but absolutely stable as well. The exception to this is when the vCore is set to auto and Load-Line Calibration (LLC) is also set to auto, where you get a roughly 5% voltage droop, as per Intel's specifications. Nevertheless, to demonstrate just how good the vCore line is, let's take a closer look at the vCore's characteristics with a one-hour OCCT stress test using our 'Overall Stable System Overclock'.


Usually, we would have two vCore charts above, one with Load-Line Calibration enabled and one with it disabled. However, on the P7P55D Deluxe, as soon as you manually select the CPU core voltage LLC gets enabled automatically. Therefore, unless a user manually disables it (and there's no reason to), this is what the vCore line will look like. As you can see, the vCore line is absolutely perfect, showing no variance from idle to load and zero ripples. Clearly, this model has well engineered CPU PWM design.

Power Consumption

All motherboard manufacturers boast that their products have the lowest power consumption and feature the latest new development in energy efficiency. Well that is what we are here to find out.

For this test, every BIOS option was reset to its default setting and the Windows Vista power plan was changed from High Performance to Balanced. Lastly, we set the ASUS EPU-6 Engine to AUTO mode to allow it to fully manage system power consumption. We also ran this test without EPU being installed on the system, to see what the difference would be.

For our idle test, we let the system idle for 15 minutes and measured the peak wattage through our UPM EM100 power meter.

For our CPU load test, we ran Prime 95 In-place large FFTs on all available threads for 15 minutes, measuring the peak wattage via the UPM EM100 power meter.

For our overall system load test, we ran Prime 95 In-place large FFTs on all available threads for 15 minutes, while simultaneously loading the GeForce GTX 280 with OCCT v3.1.0 GPU:OCCT stress test at 1680x1050@60Hz in fullscreen mode.


In bone stock form, the P7P55D Deluxe actually exhibited slightly lower power consumption across the board than the Intel DP55KG. The differences ranged from 2% to 4.5%, which is minimal but still noteworthy in the long-term. Enabling EPU didn't really rectify the situation, if anything it made it worse. While the idle power consumption dropped a bit, matching the Intel board, the CPU load and full system load values actually went up. Why? Well when set to AUTO mode, the EPU software will actually slightly overclock the processor under heavy lead load scenarios. As a result, the energy consumption obviously increases a bit. We could have set the software to maximum power savings, but it underclocks the system to such an extent that it cripples system performance while doing intensive tasks. All in all though, the power consumption differences between these two motherboards are minimal, and are frankly irrelevant when you consider that the Lynnfield/P55 platform provides the very best Performance-per-Watt on the market.