Sega Dreamcast/Hardware comparison

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Vs. PC

The Sega Dreamcast's PowerVR CLX2 GPU was the basis for the PowerVR PMX1, a PC GPU released with the Neon 250 graphics card in 1999. However, the Neon 250 lacks many of the tiled rendering features of the CLX2: the tile size is halved from 32×32 pixels to 32×16 pixels (halving the fillrate), it lacks the CLX2's internal Z-buffering and alpha test capability with hardware front-to-back translucency sorting (further reducing the fillrate and performance, as well as requiring the Neon 250 to render a Z-buffer externally), and the tiling is partially handled by software (the CLX2 handles the tiling entirely in hardware). The Neon 250 also lacks the CLX2's latency buffering and palettized texture support while VQ texture compression performance is halved, and it has bus contention due to having a single data bus (whereas the CLX2 has two data buses). The PowerVR2 was also optimized for the Hitachi SH-4's geometry processing capabilities (rather than for a Pentium II or III), while PC drivers and software were not optimized for the Neon 250's tiled rendering architecture (compared to Dreamcast games which were optimized for the CLX2's tiled rendering architecture). The Neon 250 thus had only a fraction of the Dreamcast CLX2's fillrate and rendering performance. The reduction in performance from the Dreamacst's CLX2 to the Neon 250 was comparable to the reduction in performance from the Sega Model 3's Real3D Pro-1000 to the Intel740.

The Dreamcast was generally the most powerful home system during 1998–1999, outperforming high-end PC hardware at the time. The Dreamcast's Hitachi SH-4 CPU calculates 3D graphics four times faster than a Pentium II from 1998, and faster than the Pentium III and Nvidia GeForce 256 from 1999. In addition to the SH-4's 1400 MFLOPS of floating-point performance, the Dreamcast's PowerVR CLX2 GPU has an additional 200 MFLOPS for tiled rendering, and has a fillrate of 3.2 GPixels/s with opaque polygons and 500 MPixels/s (500 MTexels/s) with opaque and translucent polygons, higher than the V3 TV SE's 200 MPixels/s (400 MTexels/s) and GF256's 480 MPixels/s (480 MTexels/s).

The DC's 800 MB/s CPU–GPU transmission bus is faster than the V3's 533 MB/s AGP bus (2x AGP 2.0) and has a higher effective bandwidth than the 1064 MB/s transmission bus from a PIII 800EB (133 MHz FSB) to GF256 (4x AGP 2.0) due to the DC's more efficient bandwidth usage, including its lack of CPU overhead (from operating system) and the CLX2's tiled rendering architecture: textures loaded directly to VRAM (freeing up CPU–GPU transmission bus for polygons), 8:1 VQ texture compression (higher than V3's 4:1 compression and GF256's 6:1 S3TC compression), on-chip tile buffer with internal Z-buffering, and deferred rendering (no need to draw, shade or texture overdrawn polygons). The CLX2 was capable of order-independent transparency (which the V3 and GF256 lacked) and Dot3 normal mapping (which the V3 lacked). The CLX2's rendering throughput is 7 MPolys/s, with game engine performance peaking at 5 MPolys/s; in comparison, a Celeron 300A 450 MHz (100 MHz FSB, 364 MFLOPS) with V3 TV (183 MHz) renders 750,000 polys/s, a PIII 800 (800 MFLOPS) with V3 TV SE (200 MHz) renders 1.8 MPolys/s, and a PIII 800 with GF256 has a peak rendering throughput of 6.7 MPolys/s and peak game engine performance of 2.9 MPolys/s.

Dreamcast game engines rendered 50,000–166,666 polys per scene (3–5 MPolys/s), while PC game engines of 1999 rendered up to 10,000 polys per scene (1–1.6 MPolys/s). Character models in particular were significantly more detailed in Dreamcast games than in PC games during 1998–1999.

Vs. PlayStation 2

Compared to the rival PlayStation 2, the Dreamcast is better at textures, anti-aliasing, and image quality, while the PS2 is better at polygon geometry, particles, and lighting. The PS2 has a more powerful CPU geometry engine (6.2 GFLOPS Emotion Engine), higher translucent fillrate (2.4 GPixels/s), and more main RAM (32 MB, compared to DC's 16 MB), while the DC has more VRAM (8 MB, compared to PS2's 4 MB), higher opaque fillrate (3.2 GPixels/s), and more GPU hardware features, with CLX2 capabilities like tiled rendering, super-sample anti-aliasing, Dot3 normal mapping, order-independent transparency, and texture compression, which the PS2's Graphics Synthesizer GPU lacks.

With larger VRAM and tiled rendering, the DC can render a larger framebuffer at higher native resolution (with an on-chip Z-buffer), and with texture compression, it can compress around 20–60 MB of texture data in its VRAM. Because the PS2 has only 4 MB VRAM, it relies on the main RAM to store textures, but the PS2's CPU–GPU transmission bus for transferring polygons and textures has a bandwidth of 1.2 GB/s; while 50% faster than the DC's 800 MB/s CPU–GPU transmission bus, the DC has textures loaded directly to VRAM (freeing up the CPU–GPU transmission bus for polygons) and texture compression gives it around 2–6 GB/s of effective texture bandwidth. DC games were effectively using 20–30 MB of texture data (compressed to around 5–6 MB), while PS2 games up until 2003 peaked at 5.5 MB of texture data (average 1.5 MB).

PS2 games up until 2003 rendered up to 7.5 MPolys/s (145,000 polys per scene), with most rendering 2–5 MPolys/s (average 52,000 polys per scene); in comparison, DC game engines rendered up to 5 MPolys/s (166,666 polys per scene), with most games rendering 2–4 MPolys/s (average 50,000 polys per scene).

The DC is more user-friendly for developers, making it easier to develop for, while the PS2 is more difficult to develop for; this is the reverse of the 32-bit era, when the PlayStation was more user-friendly, and the Saturn more difficult, for developers.

Vs. GameCube and Xbox

The Xbox and GameCube were both more powerful than the Dreamcast, but the Dreamcast had several hardware advantages. The Dreamcast has a higher opaque fillrate (3.2 GPixels/s) than the GameCube and Xbox (both under 1 GPixels/s). The Dreamcast's translucent fillrate (500 MPixels/s) was comparable to the Xbox's practical fillrate (250-700 MPixels/s), but lower than the GameCube's fillrate (648-800 MPixels/s). The Dreamcast's SH-4 CPU has a faster floating-point performance (1.4 GFLOPS) than the Xbox's PIII-based CPU (733 MFLOPS), but lower than the GameCube CPU's floating-point performance (1.9 GFLOPS). However, the GameCube and Xbox have T&L GPU with floating-point capabilities, giving both faster floating-point performance than the Dreamcast.

Graphics comparison

See Sega Dreamcast technical specifications for more technical details on Dreamcast hardware

System	Sega Dreamcast (1998)	PC (1998)	PC (1999)
Geometry processors	Hitachi SH-4 (200 MHz)	Intel Pentium II (450 MHz)	Intel Pentium III (800 MHz)
Floating-point operations	1400 MFLOPS	350 MFLOPS	800 MFLOPS
Geometry calculations	10 million polygons/s	2.5 million polygons/s	6.7 million polygons/s