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AMD’s Integrated Gambit

690G Looks to be Better By Design

By Josh Walrath

Thermal and Power Analysis

            In nearly every situation, heat and power are often limiting factors to high performance computing.  Take for instance the Home Theater PC.  People do not want a big, loud, and cumbersome PC sitting in the middle of their media center, and so users often have to compromise on the performance of their HTPC.  Luckily we are beyond the Pentium 4 days, and both Intel and AMD have embraced the idea of lower power consumption and lower heat production.

            The temperature tests were held in the same room with an ambient temperature of 78 degrees F.  All components excluding the motherboards and processors are the same (monitor, keyboard, mouse, etc.).  I used a laser thermometer that is accurate to within 2% of the actual temperature.

            For the CPU temperatures I measured the base of the heatsink.  The AMD processor used a stock AMD supplied heatsink (no copper or heatpipes) while the Intel unit used the stock heatsink (copper base/plug with aluminum fins).

            First off we should realize that the X2 5600+ is a very different bird than the year old FX-62 that first introduced the AM2 platform.  AMD uses continuous process enhancements at their fabs to help increase yields, speed bins, and power consumption through the lifetime of a product.  So a 2.8 GHz X2 in 2006 would be a 125 watt product, while the 2.8 GHz X2 in 2007 is now an 89 watt product.  Even with stock cooling the X2 5600+ runs very cool.  At load it does not go above 100 F.

            The Intel processor does run a bit hotter, but the difference is not all that extreme.  It will heat up a smaller case a little faster, but as we will soon see the CPU is not going to be the main culprit for heat production on the Intel side.  Even at load the processor does not heat up dramatically with the stock cooler.

            The next test is to show how hot the northbridges on these motherboards get.  On the AMD side the northbridge contains the HT controller, the integrated graphics portion, and the PCI-E lanes.  On the Intel side it contains the memory controller, the FSB controller, integrated graphics, and the PCI-E lanes.  The Intel chip, due to the memory controller, is a bit more complex than the AMD part.  I took temperature readings directly off the heatsink covering the chips.  The heatsink on the AMD board is relatively small, while the heatsink on the Intel board is actually much larger.

            Even though it has a smaller heatsink, the 690G runs much cooler than the G965.  The G965 heatsink would get so hot that I was unable to keep my finger on it for more than a second without experiencing pain.  The AMD part kept relatively cool, and I could keep a finger on it indefinitely.  The G965 is a hot, hot running part, and probably should be actively cooled.

            For the power tests I plugged the power supply into a P3 Kill-a-Watt power meter and read the maximum power pull on each of the systems.

Next:  Test Results

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