Diamond HD 3870: Detailed Features

The reverse side of the Diamond HD 3870 is thankfully devoid of any memory chips, with each of the eight 64MB BGA chips of GDDR4 memory located on the front. As a result there is no need for any form of cooling plate such as found on the HD2900XT. The only retention mechanism is the four post backplate with spring retention screws.

Here is the marvel behind Diamonds HD 3870 the RV670 GPU manufactured with 666 million transistors at 55nm by TSMC. This is a retail sample, and the only significant numbers we can discern are the manufacture date - week 44 of 2007. The accompanying 64bit BGA GDDR4 memory chips are manufactured by Samsung and carry the model number K4U52324QE-BC08. With 0.8 ns latency, that equals 1250MHz (2500 MHz effective).

Remember that the memory on the Diamond HD 3870 is clocked at 1125. This means the memory onboard is under-clocked a full 125MHz (250 MHz effective), leaving plenty of room for memory overclocking.

Regarding overclocking; The Catalyst Control Center's Overdive feature allows for automatic overclocking via the Auto-Tune option. However, we still prefer a more hands on approach to overclocking and recommend RivaTuner for its low level driver independent clock adjustments, and its more complete hardware monitoring.

Using RivaTuner's monitoring software we see the stock cooling set-up on the Diamond HD 3870 does an adequate job of maintaining the idle temperature below 50c with an ambient room temperature of 21c. This is of course at a lower core operating frequency, referred to as 2D clocks. However, there is virtually no noise from the fan at idle.

As we turn things up we noticed a strange issue. Despite even 100% load on the GPU the fan never spun up beyond its constant 30% duty. However, even at a steady 30% the cooling was sufficient enough to keep 100% GPU load temperatures around 63c, a testament to the smaller manufacture process.

Now that we know a little of the workings of the Diamond HD 3870, let's see what AMD/ATI's lattest GPU can do when we put it through the rigors and run some benchmarks.

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