Gigabyte ATI Radeon HD 4770 512MB

Gigabyte Radeon HD 4770

In terms of specification, the GPU is a reference RV740 design. Featuring 128 five-way superscalar shader units (or 640 stream processors) which is twice as many as the RV730 chip used in the Radeon HD 4670. The chip is manufactured on a TSMC 40nm process, which makes for less power consumption, less heat and ultimately greater overclocking potential: all of which are invariably good things.

ATI has taken advantage of this extra potential and clocked the core of its new GPU at 750MHz which is 125MHz faster than the HD 4850 and equal to ATI’s excellent Radeon RV770 chip which lies at the heart of the Radeon HD 4870.

What's the Difference?

Unfortunately unlike our "reference" design sent to us by AMD, it seems that despite using the same PCB, Gigabyte has been pulling off components left, right an centre in a bid to cost-down the card. If you look at the pictures below, there are clearly many of the capacitors missing, as well as one of three MOSFETs in every power phase, although there still remain 3+1 (core and memory) power phases present.

Inevitably this is likely to limit the overclocking as the available power delivery and smoothing is more limited than our "AMD reference design".


Another difference between the two cards is the custom cooler. On the Gigabyte, the air isn't exhausted directly out the back of the case as it is in the reference design which may be an issue in smaller cases with limited airflow. The reference design also utilises heatpipes to better transfer the heat from the GPU to the heatsink fins.

In addition to that, that Gigabyte has done away with the heatsink that ATI bolted to the memory, which could be another issue. When we initially tested the HD 4770 we found that this black heatsink got hotter than Liv Tyler smothered in whipped cream and strawberries, so we were surprised to see it removed altogether. Finally the fan is connected to the PCB using a 2-pin connector which means that there is no fan speed control, resulting in the fan spinning the same speed no matter what the temperature is. Considering that it's not the quietest cooler we've seen, this isn’t really ideal.


When we performed thermal testing of the reference card we found that it ran at a very respectable 74 degrees under load and a cool 46 degrees at idle. Clearly it isn’t the most thermally demanding chip on the market so perhaps Gigabyte could get away with the cooler modifications.