220 MHz core, 275 MHz memory; OEM cards are clocked 200 MHz core, 250 MHz memory. To further improve analog image quality, 5th order low-pass filters are used. Performance For a top-of-the-line, and rather expensive card ($399 USD), the Matrox Parhelia's 3D gaming performance was well behind NVIDIA's older and similarly priced GeForce 4 Ti 4600. The Parhelia was only competitive with the older Radeon 8500 and GeForce 3, which typically cost half as much. The Parhelia's potent performance was held back by its comparatively low GPU clock speed (220 MHz for retail model, 200 MHz for OEM and 256 MB models), initially believed by many commentators to be due to the large (for that time-frame) transistor count. However, ATI's Radeon 9700 was released later that year, with a considerably larger transistor count (108 million vs. 80 million), on the same 150 nm chip fabrication process, yet managed a substantially higher clock (325 MHz vs. 250 MHz). The card's fillrate performance was formidable in games that used many texture layers; though equipped with just 4 pixel pipelines, each had 4 texture units. This proved not to be an efficient arrangement in most situations. Parhelia was also hampered by poor bandwidth conserving technologies/techniques; ATI introduced their 3rd gen HyperZ in Radeon 9700, NVIDIA touted Lightning Memory Architecture 2 for the GeForce 4 series, Matrox had no similarly comprehensive optimization approach. While the Parhelia possessed an impressive raw memory bandwidth much of it was wasted on invisible house-keeping tasks because the card lacked the ability to predict overdraw or compress z-buffer data, among other inefficiencies. Some writers believed Parhelia to have a "crippled" triangle-setup engine that starved the rest of the chip in typical 3D rendering tasks . Later in Parhelia's life, when DirectX 9 applications were becoming quite prevalent, Matrox acknowledged that the vertex shaders were not Shader Model 2.0 capable, and as such not DirectX 9-compliant, as was initially advertised. Presumably there were several bugs within the Parhelia core that could not be worked around in the drivers. However, it was all a bit of a moot point because Parhelia's performance was not adequate to drive most DirectX 9-supporting titles well even without more complex shader code weighing the card down. Sales Despite the lackluster performance for its price, Matrox hoped to win over enthusiasts with the Parhelia's unique and high quality features, such as "Surround Gaming", glyph acceleration, high