Sunday, April 22, 2007

Another little TidBit about Intel

Not that you wanted to see this.

Someone called me out in one of the Previous posts where I stated this:

not to mention the 35watt processors of which AMD has 6... and Intel has none.

The person then proceeded to link me to several Wattage Specifications for Intel Processors which indicated that the Conroe and Memron chips were playing about in the sub 65watt power arena. Not so fast. Comparing AMD processors to Intel Processor's isn't as simple as Intel would like you to believe. While Intel promotes the WoodCrest processors of averaging about 40watts, Intel is not promoting the same thing that AMD is promoting.

The first point to be made is that Intel likes to post the average amount of watts consumed by their processors. This was noted with the Pentium4 in which realistic heat output was far higher than the reported heat leves by Intel. The changing factor was the wattage consumption, which was way out of line with the reported amount by Intel.

With the Conroe based designs, Intel has not appeared to change their strategy in regards to listing wattage consumption. The numbers given by Intel are for the normalized workload, and don't indicate the wattage consumption in a high continuous stress enviroment.

The second point is that AMD typically lists the maximum thermal envelope. When you buy a 65watt processor from AMD, chances are unless you overclock that processor, your wattage consumption won't come close to 65watts. When you buy a 35watt Athlon64, again, your wattage consumption in a high continuous stress enviroment... will be 35watts.

There is one architectural difference between the Intel Processors and the AMD processors that allow for this to happen, and why you can't compare the Wattage and Heat output of an Intel Conroe to that of any AMD Athlon64. Just one tiny little difference...

AMD's Memory controller... is on the processor.

Catch that? When you buy an Athlon64, you aren't just buying the processor, you are also buying the memory controller to go along with it. This is just one of the reasons why AMD motherboard costs are generally lower than Intel motherboard costs.

It is also the reason why AMD can be more consistent in delivering a constant state of energy usage to their processors, and why you can't compare the Wattage consumption of Intel Processors to AMD Processors.

In an Intel design, you have to add the wattage cost of the northbridge chipset to the wattage cost of the processor in order to get a clearer picture of the energy consumption when comparing an Intel Processor to and AMD processor. However, that comparison is also going to be imbalanced in AMD's favor, period.

In an Intel motherboard design, in addition to housing the Memory controller, the Northbridge also has to house the I/O operations for the PCI Bus, an AGP bus if one is present, as well as the handles for any Integrated sound outputs, and the handles for any integrated network device, and so on. While these operations could be pushed off onto a Southbridge chipset, and many are, it doesn't change the fact that the Intel Northbridge is going to be more complex than an "equivalent" from AMD.

In an AMD motherboard design, in most cases the Northbridge will be cooler running because of no memory controller, but will often be offset by including more functions that were typically split between a Northbridge and Southbridge. One of the terms that you might hear getting tossed around today is "Single Chip Design," which is where a single Northbridge chip handles all of the I/O operations within the system.

So, in order to get a clearer picture of Wattage consumption, you have to keep going out... And include not just the Processor, but the entire motherboard.

That's why a majority of server vendors state that AMD systems are cooler running, period. AMD accounts for the heat output and the energy consumption of the memory controller in the same space as the Processor... Intel Does not.

So, I'm going to stick by my statement that Intel doesn't offer any 35watt, or even 40watt processors. In order to compare it to AMD, I would either have to:

A: Add the thermal information and wattage consumption figures for the Intel Northbridges
B: Subtract the thermal information and wattage consumption from the AMD processors.

Call it a hunch, but I'd very surprised if the combination of Processor and Northbridge would allow Intel to have any Processors below the 60watt mark.
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