Re: PCI card current loads

["Thomas Schutt" <Thomas_Schutt@splashtech.com>]

Peter;
   You are absolutely right. Leaving it up to software to prevent 
motherboard problems or damage is asking for trouble. And is therefore 
bad design. My point was there are some nasty cards out there. Plus with 
the efforts to have low stand by currents, the dynamic load from a power 
supply stand point is going to get worse with no controls.

   As a board designer we can minimize these problems or target systems 
that can handle the card. As motherboard/system designer you need to 
plan for the worst or control the add in cards. It would probably help 
the power supply and system vendors if the PCI spec included a dynamic 
load specification for add in cards.

   By the way it's not really how much memory you have, but how much is 
cycling in parallel and how fast. If absolute performance is the goal, 
the design will be wide, fast and power hungry. For example, has anyone 
measure the step responce in current draw when dynamicly switching a 
multi sync 21" monitor and graphics card from VGA mode to 1600x1200 
pixel x24 bit resolution ( <60 MBytes/sec to >400 Mbytes/sec )? Or does 
anyone know the step responce to initiating a 3D operation on the new 3d 
graphics cards? Both may be significant to the power system designer.

- tom_schutt@splashtech.com
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