Does Cycles Use More Single or Double Precision Math to Render?

I am looking at video cards, and I was wondering which would be more of a figure of merit for Cycles, floating point: single or double?

Background: Often the Tflops would seem easier to compare rather than trying to work up the Shader Units, GPU Speed, and Memory Speed/Bandwidth.

Cycles does not use double precision.

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Thank you : )

I…am dreadfully aware that there are faster video cards than what I am rendering on.
A 6K, 32-bounce render, almost done : )

are you using denoisers? you may be able to cut that time significantly-

and yes. a new card will be a life changer, if you render that type of stuff often you should buy a really big card with a ton of cuda cores and a ton of Vram.

Sometimes I use nVidia denoise, ran from the command-line, though the version I have only takes .bmp’s as it errors with .png’s. Yes, I know that there is a Rhino plug-in. I should check out the GUI to see if it’s handy, but I want both copies: with and without denoise saved.

nVidia denoise does clean the image, and does so without banding. On the downside, it sometimes extinguishes small details like grain and texture.

[Because it only take a second to do a 4k image, I thought that it could have been made better for still-renders. I realize the nVidia made it for real-time rending to help with their RTX. If they had a mode where an entire minute could have been devoted to the same problem, the result might have been even better.]

I am rendering on an old GTX 1080, in a 12-core AMD 3900x. Even my Quadro A3000 in my laptop is faster than either, but it shouldn’t do 24-hour renders, as I have already lost a fan in my laptop once in a year, from doing coffee-shop renders.

Last evening, I was able to initiate a 8K render on a 8GB GTX 1080, so it will be faster than the CPU, though it’s slow going.

I spent the evening looking at video cards. (I’m having health problems, and am living on a fixed income, so money is tight, but I need to do something about this. I have 2,000 subscribers, so I should see if nVidia would front me something : )

I wish nVidia made a RTX 4070 or 4070ti with 16GB or memory. I’m a little worried about getting the 12GB card, as you know I like nice big textures and large renders.

I might get a 4080 FE. They blow a lot of air out of the back, which is a plus because I have a rackmount case. They appear to be more of a blower than a stirrer. Still, $1200 is a lot of money to me, and most people.

Then the problem is: the 4090 almost makes sense because it has 24GB of the memory, and that will also determine the useful life of the card.

[In CPU’s buying that last little bit doesn’t buy you much more.
When gaming, buying GPU’s, spending more only gets you a few more frames, which doesn’t matter when it’s new, but when things get slow it does.]