X-bit labs

Roundup of 7 Contemporary Integrated Graphics Chipsets for Socket 478 and Socket A Platforms (page 13)

Category: Chipsets

by Tim Tscheblockov

[ 07/05/2004 | 11:09 AM ]

3D Image Quality

Save for a couple of annoying cases, the integrated chipsets rendered the scene well enough. Only two chipsets acted up. As you may have guessed, they are the ones from VIA and SiS.

First, all chipsets from VIA and SiS didn’t display fog in IL-2. Second, the graphics from SiS has a certain optimization of bi-linear filtering, which makes any smooth gradients into ugly mosaic. This optimization is enabled at multi-texturing in all OpenGL-using games. We covered this matter in more detail and color in our SiS 315 review.

2D Image Quality

The quality of the image output to the monitor is a sore point of integrated chipsets. They are traditionally inferior to external graphics cards in this respect, mostly due to two reasons: first, integrated graphics processors usually have a lower-frequency RAMDAC than discrete graphics chips. A RAMDAC with a high conversion frequency doesn’t guarantee the quality, but it is a mandatory requirement to reach the highest image precision at high resolutions and high refresh rates. Second, an integrated graphics processor, unlike a discrete GPU, is not a separate unit, but only a functional block of the chipset. Thus it finds itself in an unfavorable environment, next to the other functional units who may bring in noise or cause cross-talk, being located on the same die as the graphics core. Evidently, it takes longer routes to transfer the video signal to the monitor connector, and the lines are laid out among other signal lines.

So, let’s evaluate the onscreen image quality as provided by the mainboards participating in our today’s tests.

I attached a 19” Hitachi CM-661ET CRT monitor to check out the image quality. To support my subjective impressions, I just made snapshots of the onscreen image I got with different mainboards and took them together into a single picture. The original image was a window with Windows’ Explorer:

So, 1024x768x32bit, 85Hz refresh rate:

The image quality is good. A slight fuzziness can be discerned on the VIA KM400, but it is really hard to see.

Next, 1280x1024x32bit, 85Hz refresh rate:

Now we see a noticeable, sometimes strong blurriness. It is the strongest on the SiS661FX and the VIA KM400.

The mainboards based on the i865G and the nForce2 IGP provide the best visual quality.

The next mode: 1600x1200x32bit, 75Hz refresh rate.

It’s quite bad here, especially with the SiS661FX and the VIA KM400.

So, you can expect to see a crisp image attaching a CRT monitor to an integrated chipset and setting the resolution to 1024x768 and the refresh rate to 85Hz.

In the 1280x1024 resolution, all the mainboards, save for the ones based on the SiS 661FX and the VIA KM400, also outputted a sharp picture onto the monitor.

The image quality degenerated in the 1600x1200@75Hz mode, especially with the SiS661FX and the VIA KM400.

Still, you shouldn’t forget that these results only describe the specific mainboard working with the specific monitor. Mainboards from other manufacturers may behave differently, depending on the wiring quality. We have a good example already: the SiS661FX- and the SiS741GX-based mainboards. These chipsets have identical integrated graphics controllers, but the mainboards come from different manufacturers and give out a picture of varying quality: the SiS741GX board, although it comes from ECS, provides a higher image-output quality than ASUS’ one.

Attached to an LCD monitor, an integrated chipset outputs a better picture as a rule. First, there’s no need to set a high refresh rate for an LCD monitor: unlike CRT monitors, LCD panels don’t flicker during refreshes. Second, attached via an analog cable, an LCD monitor digitizes the image before outputting it and thus has an inborn immunity to the distortions of the front of the signal, i.e. to the blur which would be noticeable on a CRT monitor. Of course, this immunity has its limits and cannot help in critical cases.

I proved all these suppositions at practice taking a 17” LCD monitor with a native resolution of 1280x1024 and attached it in the 1280x1024x32bit mode at 60Hz refresh rate. The outcome is visible in the snapshots:

ATI RADEON 9100 IGP

ATI RADEON 9000 PRO IGP

SiS661FX

Intel 865G

NVIDIA nForce2 IGP

SiS741GX

VIA KM400

My expectations came true: all the integrated chipsets, save for the SiS661FX and the VIA KM400, gave out practically perfect images. The SiS661FX and KM400 still produced pictures of a higher quality than those they drew on the CRT monitor in the 1280x1024 resolution.