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Improving your performance

Many users are not aware that the speed and capability of their computers could be down to their choice of graphics card

When buying a new computer, most people are quick to inform you about the processor clock speed. 'It's a 2.2GHz P4!' you will hear them exclaim excitedly. Some will go on to dribble over the half gigabyte of RAM and perhaps extol the virtues of the pretty LCD flat panel monitor. But many will barely know the memory capacity, let alone the type of graphics card installed, a factor that will make or break the usability of their new toy.

In recent years, graphics card manufacturers have increased performance dramatically while slashing retail prices. One such company, which sells high-performance cards at relatively modest prices, is nVidia. Offering graphics cards for everything from the optimised home gaming machine to the professional graphics workstation, nVidia is committed to a high level of research and development investment.

But what makes the difference between a graphics card that enables you to whiz around a dungeon killing everything in your path and a card that increases the speed and flexibility of your CAD workstation in the office? I have looked at representatives of each, the Quadro family for the tough stuff and the GeForce family for gaming.

The Quadro performs almost all its calculations on the hardware, whereas the GeForce uses software to resolve the graphics. Being hardwarebased makes Quadro significantly quicker than the equivalent approach using software.

You will pay more for this increase in power: the GeForce family starts at about £30; the Quadro at a few hundred pounds. Quadro cards have at least six key areas in which they outperform the GeForce card, including anti-aliasing, clip regions, clip planes, memory management, overlay planes and CAD application optimisation.

Anti-aliasing Many CAD applications offer the option of using antialiased points and lines. With this option turned on, component edges can be viewed as precisely as possible without encountering the jagged-line effects that are associated with lines displayed on a rasterised display.

Clip regions

CAD applications rely heavily on popup windows. These often occupy the full screen, so the result is many overlapping windows, which may noticeably affect visual quality and graphics performance.

Vidia's graphic processing unit (GPU) architecture manages the transfer of data between a window and the overall frame buffer by 'clip regions'. If one window overlaps another, then the transfer of data from the colour buffer to the frame buffer must be broken into a series of smaller, discontinuous rectangular regions.

These are referred to as 'clip regions'.

Clip planes

These allow sections of 3D geometry to be cut away so the user can look inside solid objects.

Many professional CAD applications, including MicroStation, allow users to define clip planes.

Memory management Quadro memory management allocates and shares memory resources efficiently between concurrent graphics windows and applications. In many situations, this affects application performance and so offers demonstrable benefits over the consumeroriented GeForce GPU family.

Overlay plane support

The user interfaces of many professional applications often require elements to be drawn interactively on top of a 3D model or scene. The most obvious example is the cursor, which is drawn in front of any 3D object or window.

You may have experienced 'screen debris' in the past when the movement of the cursor leaves 'bits' in it wake.

Another example of a user interface element is a pop-up menu.

Unfortunately, when these menus pop up in front of an OpenGL (Open Graphics Language - the benchmark for fast rendered on-screen graphics) window, they cause the contents of the window beneath to become 'damaged'. CAD applications tend to use overlay planes to combat this issue of debris, but your graphics card needs to support this function for you to get the benefit.

CAD application optimisation

Vidia works closely with most CAD application developers to take full advantage of all the features of each CAD application.

It's not a game While the benefits of hardwareoriented features such as anti-aliased points and lines, clip regions, clip planes and overlays are somewhat hidden from an end-user's workflow, support for these features will translate directly into productivity benefits. Using a decent graphics card will improve the screen clarity and speed of manipulation of your drawings and models.

Costing in the region of £500 without VAT, the nVidia Quadro4 750 XGL Graphics Controller is a high-performance, mid-range graphics card with the ability to render 60 million lit, shaded, and trilinear-textured triangles per second.

It also benefits from 128MB of fast Double Data Rate (DDR) memory and its second-generation nfiniteFX II Engine makes procedural effects (high-quality texture mapping) possible in real time. These features are complemented by the nView multi-display technology that lets users spread their work across dual monitors.

So next time you suffer problems do not assume that you need to rush out and buy a new machine. A professional graphics card could have a greater impact on performance than another 500MHz of processor speed.

Joe Croser can be contacted at joe@croser. net

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