In our time with ATI, they spent a significant amount of time talking about their new POWERPLAY technology. The Mobility Radeon 7500 has a significant amount of its design specifically targeting the ability to get the most performance out of the least amount of power.

One of the early power management initiatives ATI pioneered is known as clock gating. This is an activity-based, dynamic technique that automatically turns off the clocks of idle parts of the graphics chip. The Mobility Radeon 7500 has more than 30 gates in the chip dedicated specifically to this power saving technology. For example, if the 3D engine is not in use, the clock branches normally operating this block are turned off.

As with all technologies in the computer industry, ATI's implementation of this technology has improved over time as the number of independently controlled clock branches has increased.

The Mobility Radeon 7500, using ATI's new POWERPLAY technology, has the ability to change its clock speed and voltage usage dynamically based on your performance and power conservation needs.

At full speed, the 7500 runs at 270MHz core, 210MHz (DDR) memory speed, operating at 1.5v. In this mode, the Mobility Radeon 7500 outperforms anything available today by a large margin from what we've seen. When you are unplugged from the wall and running off battery power, the chip reduces its clock speed to 66MHz core, at just 1.2 volts, while the memory stays at 210MHz. In this mode, 2D and simple 3D applications run well, and DVD playback remains smooth. This mode can reduce power consumption as much as 45%.

As the user, you always have the ability to disable POWERPLAY if you need full performance when running off battery power.

Another of the many ways the Mobility Radeon 7500 helps conserve notebook power should be very familiar to any of you who have used a Rage128 or Radeon based card for DVD playback.  The 7500 fully supports ATI's excellent Motion Compensation and iDCT acceleration, pioneered with the ATI Rage128 series of chips.  The benefit of this is quite surprising when you take into account all the other components involved in DVD and Video playback.

During our meeting, we were treated to a 3 minute clip of the lobby scene running from the Matrix DVD. This was run with no frames dropped while the laptop was running in power save mode at 66MHz.  This high-action scene uses only 15% CPU power when run on a 1.13GHz Pentium III.  With CPU usage that low, the CPU can clock itself much lower which can contribute significantly to the power savings.  Keeping in mind that laptop CPUs can top 15 watts power draw at full load, while the Mobility Radeon 7500 draws roughly just 0.9 watts of power during accelerated DVD decoding, you can begin to see what kind of savings you are looking at.  Feel free to play your own DVDs on that long plane flight instead of the drivel airlines try to feed you, without worrying about running out of battery power...

POWERPLAY also has an advanced feature which can reduce the LCD refresh rate when the notebook is operated in battery mode.  Given that the LCD is one of the most power hungry components in a laptop this can be quite beneficial.  I asked the ATI about this in our meeting, and the reduced refresh rate is around 50Hz as opposed to the normal 60Hz seen on LCDs.

All of these power saving techniques help the Mobility Radeon 7500 to reach never before seen mobile graphics performance, while accomplishing it at an extremely low power cost.

Memory Interface

The Mobility Radeon 7500 builds on the original Mobility Radeon in providing a powerful and flexible memory interface to notebook manufacturers.  The Mobility Radeon 7500 can support 16MB or 32MB of integrated ram built into the chip (note: this isn't eDRAM, but memory chips built into the same package as the graphics core), as well as discrete memory (off chip) up to 64MB.  There are 3 different primary memory configurations the Mobility Radeon 7500 can work in.  Here's how it breaks down:

Using only discrete memory you can have 16MB to 64MB ram using an external 64bit or 128bit memory interface.  This is known as the "P" variant.

The CSP-16 variant has 16MB internal memory, and an optional 16MB external memory for a total of up to 32MB.  Just using the 16MB internal gives you a 64bit memory interface, while having 16MB internal + 16MB external runs at 128bit.

The CSP-32 variant has 32MB internal memory, running at 64bit.  Adding the additional 32MB external memory (for a total of 64MB) runs at 128bit.

So, to sum that all up you can have:

• 128bit memory interface using only discrete memory.
• 64bit internal + 64bit external = 128bit interface when using integrated and discrete memory in combination
• or 64bit internal memory interface using exclusively internal memory

The advantage of the flexibility of the memory controller resides in the ability for notebook manufacturers to integrate full 128bit memory configurations while reducing the design complexity.  The flexible memory interface, tied together with the advanced power management features of  POWERPLAY, allows notebook manufacturers to scale the memory and system performance appropriately for the power, cost and performance requirements of mobile computing ranging from value and ultra-portable notebooks to the most powerful desktop replacement machines.