Laptop or Desktop no Longer a Valid Question? Part 2 of 3

Author: Tony Stockill

The main heat generator in both laptop and desktop is, of course, the processor. Beginning with the intel 8086 16-bit microprocessor, incorporating almost 30,000 transistors, through the 80286, to the 80386 32-bit microprocessor. This i386SX initially with 275,000 transistors was also produced as a cut-down version, the i386DX with a 16-bit external bus to reduce circuit overheads in the PC. Another version, now specifically designed for laptops, the i386SL, had circuitry to save power, such as sleep mode, etc. this brought the transistor count to around 3x that of the i386DX.


Notably at this time, AMD introduced their version of the 386, which became very popular with laptop manufacturers, due to its lower heat generation, and power consumption properties.

The next generation, the i486DX introduced floating point to the capabilities, with corresponding increase in circuitry and therefore heat generation.

Since then development has proceeded through dual core processors to quad core plus other designs specifically targeted at various types of computer, such as 64-bit architecture, rather than just desktop or laptop.

When you consider that the mainframe computer in the 80's had a processor with similar capabilities to the i486DX, in a cabinet the size of a small walk-in wardrobe, with forced cooling, by air or water, which needed to be operated in a tightly controlled air conditioned computer room, you can get a better idea of the work involved in reducing the size to that of a PC and further to that of the laptop. A multi-processor involved having another similar cabinet for each processor. Further similar sized cabinets held the main memory, cache memory, and Input/Output processors. Mainframes today are trending towards multiple PC style circuitry.

Getting back to the Desktop/Laptop question, what are we going to do about all this heat we are generating? The desktop doesn't have to much of a problem, we can install a standard muffin fan to get rid of the heat, if that is not enough, add another one!

The problem is quite different in the laptop. Compact size means more heat generated, due to crowded circuitry, with less possibility of having a sufficient airflow. Heatsinks have been used from the beginning, especially on processors, but we still need to remove the heat absorbed by the heatsink. Specially designed miniature fans, with associated heat channels, draw in the air so that it flows over the heatsinks, and exhausts as a hot airflow. These cooling systems concentrate on the processor, as that is the main source of the heat. In further comments on our website http://laptopcomputerstyle.com we remark that many manufacturers have used the lap top computer's case itself as a heat radiator, as anyone who has actually used one of these laptops on their lap will attest!

A couple of years ago, the early dual core (two processors in one) Centrino Duo processor was notorious for overheating, causing the laptop to shut down when in the middle of some processor intensive operation, such as graphics or video (or both together!). The later Centrino 2 dual core processor is much more tolerant and can handle such processing with ease.

The conclusion to this article is in Part 3, where we consider the inevitable dominance of the laptop.

About the Author:
Tony is a retired computer engineer, now working from home on the internet, he regularly publishes websites, see Laptop Computer Style.

Article Source: ArticlesBase.com - Laptop or Desktop no Longer a Valid Question? Part 2 of 3