NVIDIA GeForce4 4200 Go: Bringing mobile gaming to new heights

PowerMizer: The same but different

We mentioned previously that the only thing added to the NV28 core to make the NV28M core used in the GeForce4 4200 Go is PowerMizer power management hardware. The PowerMizer hardware used in the NV28M is borrowed directly from the NV17M, meaning that the two possess almost the same feature sets. You may recall that the key features of PowerMizer (detailed here) combine to produce a chip that is much more sensitive to power requirements. Unlike in a desktop, a mobile graphics processor can not afford to draw as much power and create as much heat as it wants. PowerMizer holds back the power consumption of the GeForce4 4200 Go by implementing a number of power saving features such as dynamic clock gating and dynamic clock and voltage scaling. On the hardware side these features are comparatively very similar to those found in ATI's POWERPLAY power saving hardware (with the exception of the automatic color depth reduction which ATI offers but NVIDIA does not).

Again, NVIDIA did not provide us with the total wattage that the GeForce4 4200 Go draws nor did we have enough time with our test system to measure the power consumption ourselves (look for this in a future GeForce4 4200 Go review). What we do know is that the NV28M core in the GeForce4 4200 Go can range in voltage from 1.05 volts (idle) to 1.25 volts (full performance) and can clock scale down to 1/8th the full clock speed of the mobile core or 25MHz when the chip is running at 200MHz. We were also told the memory can scale from the full 200MHz clock speed to 100MHz while idle. The dynamic voltage scaling has been redesigned in the NV28M to reduce leakage in the chip, but again that is something that will have to wait for more in-depth testing to verify. Note that the core clock speed that the NV28M is able to go down to in a 2D static state is much lower than the lowest state of the Mobility Radeon 9000 core which can only underclock itself to an 80MHz (then again, the Mobility Radeon 9000 draws a good deal less power clock for clock than the GeForce4 4200 Go). On the flip side of the coin, the memory speed on the Mobility Radeon 9000 can dip lower than the GeForce4 4200 Go's memory can, as the ATI solution is able to go down to 80MHz.

The largest thing updated for the GeForce4 4200 Go's PowerMizer release is in the software end. PowerMizer has become more friendly in this release of the software, as one is now able to set performance of the chip to one of three settings while on AC power and while on battery power. The maximum performance mode leaves the GeForce4 4200 Go running at full voltage and core and memory speed. The maximum power saving mode forces the chip to run at the lowest mode desired, i.e. at 1.05 volts and a 25MHz core speed and a 100MHz memory speed. The balanced mode sets performance between these two and can be set to OEM preferences. Again, thanks to the limited time we had with the test unit, we were unable to test the system in anything but the maximum performance mode but we will be sure to take a look at this in future AnandTech reviews.

The functionality of PowerMizer's software side is still noticeably less powerful than that of ATI's POWERPLAY. You may recall that the Mobility Radeon 9000 implemented a new interface for the POWERPLAY functions that allowed for much smarter power management. ATI is still a step ahead of NVIDIA on this front and although the new PowerMizer front end is better than the previous version, it still leaves some to be desired (for example multiple profiles for various battery states).

Before we get to the test, here is a table comparison of the GeForce4 460 Go, the GeForce4 4200 Go, and the Mobility Radeon 9000.