Save the Power: TSMC’s 90nm Here
ATI’s Mobility RADEON X1600 is produced using 90nm process technology at Taiwan Semiconductor Manufacturing Corp. and does not have many features that distinguish it from the typical ATI RADEON X1600-series chips. However, those capabilities are designed mainly to reduce power leakage and hence to reduce the power consumption. This is exactly what is necessary to decrease power consumption significantly enough to make the RADEON X1600 viable for mobile computers.
According to ATI, the mobile flavour of the model X1600 features the following technologies:
- Back bias – a technology that applies so-called bias voltage to a transistor and increases its threshold voltage (voltage required by transistor to switch), which reduces side effect known as power leakage. Since increasing the threshold voltage effectively increases transistor switch time and thus affects clock-speed, back bias is currently used only in situations where high performance is not required, for instance, in 2D mode. ATI claims back bias reduces power consumption by up to 20%.
- Mixed Vt – using transistors with higher threshold and lower clock-speeds for data paths that do not affect performance substantially. The TSMC 90 nm process allows different transistor designs with different threshold voltages to be mixed together in a single chip design, in order to provide the optimal combination of performance and power consumption.
- Dynamic Voltage Control – while the Mobility RADEON X1600 operates at reduced clock-speed at 0.95V voltage setting it scale both clock-speed and voltage up when extra performance is required. According to the company, the voltage can be boosted up to 1.2V, whereas maximum voltage of desktop RADEON X1600 chip is 1.3V.
It is obvious that the Mobility RADEON X1600 fully supports previously introduced “PowerPlay” technologies by ATI aimed to reduce power usage by mobile GPUs, including such as Dynamic Lane Count Switching (DLCS, a technology that can dynamically disable unused PCI Express lanes) and others.
While ATI does not claim it directly, we anticipate that 20% power reduction refers to desktop X1600 model running in similar environment, but at unknown clock-speed. That said, we would not directly compare Mobility RADEON X1600 against any of its desktop counterparts.