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The Sega Dreamcast was released in 1999 (1998 in Japan) at just the time that the competition for 3D graphics on PCs was intensifying. It's my assumption that a high-end 1999 Pentium II PC with 3Dfx Voodoo2 SLI rig or new GeForce would run circles around the much cheaper Dreamcast. However, I'm not sure this wasn't mainly because of the PC just having a much faster CPU.

All I have to compare today is a Pentium 1 with a single Voodoo2 card. Aside from slightly higher resolution on the PC, it seems comparable to the Dreamcast.

Which PC 3D card/CPU combination would one have needed to purchase in 1999 just to outshine the Dreamcast's graphical performance?

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    The PowerVR is an atypical architecture, being tile-based deferred*, so it might be a beefier PC than you imagine — especially if there are heavy amounts of transparency involved, or if the title in question is fill-rate bound. But, subjectively, my P200 and Voodoo1 ran Half-Life pretty poorly. The unreleased DreamCast build looks a lot smoother. *Microsoft's primer: docs.microsoft.com/en-us/previous-versions/… – Tommy Dec 10 '19 at 19:24
  • @Tommy Quake runs smooth on my P200+Voodoo2. Haven't tried Half-Life on it. Is that the same engine as Quake, or Quake 2? – Brian H Dec 10 '19 at 19:56
  • according to the internet, it's "a heavily modified version of id Software's Quake engine". I actually think Quake II ran fairly well on that machine, though I'm imagining my contemporaneous standards for 'fairly well' were frame rates in the 20s. I stopped gaming long before the expected frame rates got really good. (And, as an aside: the exact same GPU as in the Dreamcast was available as a PC expansion in 1999, and clocked 25% higher. But it's not really a great target for DirectX or OpenGL so I dare imagine it didn't feel 25% faster than a Dreamcast, or even as fast as). – Tommy Dec 10 '19 at 21:49
  • Something else that would be to the Dreamcast's benefit would have been that the PCs would have likely been rendering at a higher resolution than the DC needed to do for TVs. – Matt Lacey Dec 11 '19 at 0:20
  • With a VGA box connected, the Dreamcast emits 720x480 (480p), which is not too far behind a PC, (from memory, I could get 800x600 comfortably from a 3dfx Voodoo). The Dreamcast did get a port of Quake III Arena, which ran pretty well if I recall. – bodgit Dec 13 '19 at 9:52
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On paper, based on the fill rate only, all the high-end graphics adapters available on PC in 1999 were at least as powerful as the Dreamcast’s PowerVR2:

  • the CLX2 in the Dreamcast ran at 100MHz, with one operation/pixel/texture per clock, and memory bandwidth of 0.8GB/s;
  • the PMX1 (PC-compatible PowerVR2) ran at 125MHz, again with one operation per clock, and memory bandwidth of 1GB/s;
  • the Riva TNT ran at 90MHz with two operations per clock and memory bandwidth of 1.76GB/s;
  • the Riva TNT2 (March 1999) started at 125MHz with two operations per clock and memory bandwidth of 2.4GB/s and up;
  • the Rage 128 started at 103MHz with two operations per clock and memory bandwidths of 1.648GB/s and up;
  • the “special” Rage Fury MAXX ran at 125MHz with two graphics processors (on Windows 98 only), for four pixels per clock and 4.576GB/s in ideal circumstances;
  • the Voodoo 3 started at 125MHz with one operation per clock but two texture units (in DirectX games), with memory bandwidths of 2.288GB/s and up;
  • the GeForce 256 SDR (October 1999) ran at 120MHz with four operations per clock, memory bandwidth of 2.656GB/s, and hardware T&L.

However the PowerVR2 and SH-4 combination could provide excellent results in games written appropriately, using the PowerVR2 triangle and tile-based rendering pipeline and the SH-4’s arithmetic operations (dot product, inverse square root). This results in quoted speeds of 7M (opaque) polys per second.

To reach that using a PC GPU only, you’d need to wait for the GeForce 256 in late 1999, with 10M polys per second. However a mid-range Pentium II with any of the above GPUs could perform the same calculations in software, and 1999 was the year of the Pentium III and Athlon, providing ever-higher levels of CPU performance.

Perhaps the safest way to answer the question is to look at the specs for PC ports of Dreamcast games. Crazy Taxi was released on PC in 2002 and requires a 500MHz Pentium III or equivalent with a DirectX 8-compatible GPU — of the PC graphics adapters available in 1999, only the GeForce 256 is officially supported. That suggests that a 500MHz Pentium III or Athlon with a GeForce 256 could at least equal the Dreamcast even on a game designed for the Dreamcast.

My memories of games in the day suggest that a lesser PC could produce better graphics than the Dreamcast, at similar resolutions, assuming PC-specific optimisations: a high-end Pentium II (450MHz), or mid-range Pentium III (300MHz and up), or Athlon (the slowest ran at 500MHz...), paired with a TNT2 would have been sufficient to outperform the Dreamcast.

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    A very nice, balanced answer. Interesting info in the LGR video about Crazy Taxi. Nods to the PC for resolution, but not frame rate. Of course, this could be more about sloppy porting than hardware specs. – Brian H Dec 11 '19 at 14:32
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I heard "on the grapevine" that Sega, with their benchmarks, felt CLX2 outperformed the PC parts of that era.

Although CLX2 'only' had peak texture & shading fill rate of 100Mp/s, it performed rasterisation and hidden surface removal at a peak rate 32x higher, i.e. 3.2Gp/s. Thus for 3D worlds where there is nearly always a reasonable amount of overdraw, the effective texture fill rate was considerably higher than 100Mp/s.

On the subject of memory bandwidth, you can't just compare raw figures:

  1. The majority of textures on Dreamcast (IIRC Sega said ~75%) were compressed at ~2bpp and thus memory traffic is reduced considerably (say around 8x saving for compressed textures assuming uncompressed is 16bpp)
  2. The Tile-Based Deferred Rendering (TBDR) scheme also meant that there was no Z-buffer traffic, which is a considerable saving given that the depth values on CLX2 were (just slightly smaller than) 32bit floats. (Other systems tended to reduce bandwidth by using lower precision, e.g. 16bits per z)
  3. Similarly, TBDR meant there was no (or didn't have to be) read-modify-writes of the framebuffer and, further, all writes were done in a coherent fashion.

There were also a number of features in CLX2 that were somewhat difficult to emulate in other graphics hardware though, admittedly, not all games made use of these.

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    Ah, thanks, that explains the 3.2Gpps figure given on Wikipedia... – Stephen Kitt Dec 13 '19 at 10:09

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