ASUS P5E3 Premium X48 Motherboard Review

EPU - Just Reporting On What It Does

There has been a lot of media discussion being made about power saving by un-named manufacturers and we have decided that we didn't want to get involved in what EPU was, instead, report on what it resulted in. Through simple testing we will explain the basic functions of the AI Gear 3 software that triggers the EPU power saving features. In order to control or view what can be manipulated, we have to install the software that not only controls but reports on what the system is running. We will then compare with CPU-Z and/or other software and come to a conclusion on what is occurring during the various states.

Initially we had no luck with the AI Gear 3 software with Windows XP when we tried installing off the CD but after in Vista, we managed to download AI Gear 3 from the ASUS web site and everything seemed to install fine, although AI Gear 3 didn't really report anything until after a few reboots. Checking the power mode controls, we were happy to find them working fine, and the system responding accordingly. So despite AI Gear 3 not reporting or really working initially, we still have the ability to see what this EPU really manipulated with the system. First, we wanted to see how it responded to XMP memory being installed so we rebooted to BIOS defaults with our XMP Corsair Dominator.

Essentially, AI Gear Knows the system is being manually controlled and stays out of its way without even loading the reporting software for the AI Gear 3 mode. This is a very positive sign that the software is still well aware of what we are doing and keeps to itself when it thinks we want it to, now, will it be able to take over if we pretend we want it to? In the second screenshot, we have setup the BIOS in the AUTO settings keeping XMP out of the equation and letting AI Gear 3 complete control over the system. A couple of the secondary voltages were adjusted manually as we don't agree with the AUTO chosen voltages sometimes. As we can see through CPU-Z & Everest, at idle, the system drops the CPU multi, FSB, and vCORE when dropping through the various modes in order to save energy. Let’s now see how a few basic tests with a UPM EM100 energy meter come up with as far as the various modes under load and at idle. The system used for benchmarking and overclocking was used in the Vista Ultimate x64 environment.

Right away we have to confess the results are skewed because with the AI Gear 3+ software, under load on the calibrated AUTO setting, we actually get a small overclock to 350*9 where as with the manual configured 333*9 stays there under load. So really, the EPU is now using more power...but you are getting a free performance increase. We initially did have issues with this feature and after a BIOS result and defaults reloaded we were able to manipulate the BIOS to disregard the XMP profile and run AUTO settings.

At idle, the results are more of what we would suspect based on the changes that happened to the system frequencies and voltages at idle. As noted, under load, the AI Gear software reported the EPU running the system above spec, but at idle, it would drop FSB below spec to 299 and the CPU multiplier to 6X as well as vCORE 0.15v to a dramatically low 0.928v. Without the EPU driver and software installed, the System still drops the multi to 6X so the frequency drops at idle, but the FSB stays at 333MHz and the vCORE remains at about 1.072v which is still low in its own respect so there is little difference between the two AUTO states over a couple hours so over months it will eventually add up, how much though is something a long term study might be able to figure out.