One of the most neglected items in the computer workstation is the PSU (an acronym for Power Supply Unit). Its purpose is to provide a constant source of stabilized power over a wide range of loads. There must be enough reserve power available that in the event of a sudden current draw, the voltage does not drop appreciably. Every time the computer is required to calculate something intensively – like revolving a 3D model or applying a filter to a large image – stability must be maintained in a number of simultaneous circuits which operate different voltages (primarily +5V and +12V) in different chips. Workstations can get incredibly hot – and hot=power draw.
No matter what the advertising wizards would have you believe, the laws of physics are implacable: If a chip is suddenly commanded to calculate intensively, it will draw more current and generate more heat. The CPU, the motherboard chipset and the graphics processor are the worst culprits. There has to be enough power available from the PSU to quench this voracious electronic thirst.
Guess what? most PSU’s are just not up to the task. Money is mistakenly saved by substituting a lower-rated Power Supply that appears to do the job just as well.
An oscilloscope image of a noisy computer signal
This image shows an oscilloscope picture of the wave form of a computer signal line. This is supposed to be a nice clean square wave showing two troughs, two plateaux and an single spike, but look at the noise that results when a PSU is running at it’s limit and just can’t provide the power! The machine would still work but how happy would you be if you could actually see that wave-form?
An underpowered PC will appear to run fine,
- but in the best case, the PSU will often be running at maximum design limits (which any engineer will tell you is not a good thing), and
- in a severe case the PC will temporarily suspend it’s calculations for a few milli-seconds (effectively throttling down) while it waits for the voltage to rise again, or
- in the worst case, the machine will act erratically and often just reboot or freeze.
Calculating the real wattage needed for trouble-free operation depends on exactly what components are in the workstation and the typical operations that the software is carrying out. That’s my job to calculate this wattage.
Did you know that most computer workstations just run at “idle” for over 98% of the time they are switched on? The problem arises in that 2% period when the machine is expected to perform that there just isn’t enough power available and the supply voltage to the components drops.
A high-end graphics and 3D workstation will typically require a PSU of between 500W and 1200W.
