Hacker News Reader

Comment by antonmks | Hacker News Reader

For GTX 680 the double precision is actually 1/24 of the single precision so it is closer to 4%. Pretty sad when comparing the performance to similar priced Radeon cards.

View on HN

This is a silicon surface area trade off between gaming and number crunching. It's a decision, not a flaw.

It not a trade-off. Consumer and HPC GPUs are using the exact same silicon... Nvidia artificially cripples, in software/firmware, the double precision performance of consumer GPUs: http://forums.nvidia.com/index.php?showtopic=204025

Artificial crippling is a bad practice, which I dislike. However, note that the GPU mentioned in your link is a low-end device.

Sometimes (I don't know about this case) the low end CPU's and GPU's are chips that have manufacturing errors in them and don't pass full quality control checks. The defective parts of the chip are then disabled with microcode (or equivalent) and sold as low-end chips. That's a good practice, a lot better than simply throwing the slightly defective chips to waste.

Even the high end consumer GPUs are crippled. For example the GTX 580 is identical to the Tesla M2090 (both 512 shaders, same GF110 chip), but the first has only a fraction of the DP performance of the second. What I am telling you is a pretty well-known fact...

All of you who want inexpensive DP performance should look at AMD Radeon cards. AMD does not cripple any of its GPUs.

Yes, they have disabled parts because NVidia was having serious yield issues that generation and didn't have enough perfect chips to make a product line from them. If you want to be an AMD partisan, just say that NVidia cripples their cards because their silicon engineers aren't good enough to get acceptable chip yields without doing so.

No, they did not disable it because of yield issues... The double precision logic is there, on the consumer GTX line, not disabled. Nvidia just limits the rate of DP instructions per clock for merely differentiating it from the enterprise Tesla line. Even Nvidia admits doing so.

I hate that, but I guess it makes sense from a business perspective.

Oh, I thought you were talking about the fused off shader groups. Yeah, you're totally right about the DP stuff.

Reply on news.ycombinator.com