Sunday, July 14, 2013

The Power of the Shadow

I just upgraded my computer, yay!  Well, actually the Resident Geek did the upgrading (thank you, dear!)  I got a new solid state drive that opens Windows and programs like lightning, and I got a new Nvidia GeForce GTX 670 video card (the Resident Geek is hollering, "with TWO gigabytes of memory and a factory overclock!"  I figured that this would be a shoo-in for running Second Life, even with the advanced lighting model and shadows enabled.

And in fact, it does a great job!  I don't see any marked improvement over my previous GTX 560 Ti, but then again I am driving two new, larger monitors (27 inches, 2560x1440 pixels).

But as an experiment, I enabled my GPU-Z monitoring utility and watched what happened when I ran SL.

At idle, with nothing going on, the card loafs along at about 35-40 deg C, fan at 30%, GPU load at zero to 4%, power at about 12%.

With Second Life running, and water reflections, windlight, and local lights on, the power consumption goes up to about 45-50%, the GPU load goes up to about 30-40%.  Temperatures on the GPU rise to around 50-55 deg C.

But when I enable the advanced lighting model and  Power consumption leaps to 100%, sometimes even a few percent over.  GPU load goes to 98-99%.  Fan speed increases to about 60%, and temperatures rise up to 87-90 deg C!

I always knew shadows put a huge demand on a graphics card, because they cut my frame rate almost in half.  But this was an eye-opener.  It is amazing how much the new "eye candy" demands from even "high end" video cards.

I was concerned when I saw those 90 degree temperatures (remember, that's degrees Celsius, where 100 is the boiling point of water.)  I have always tried to keep my electronics under about 60 deg C.  But the Geek did some research and it turns out that modern graphics cards are designed to run hot.  I should not get worried unless the temps start to edge into the high 90's or low 100's.

I also verified something else I'd read:  Second Life does NOT benefit from an SLI setup (multiple graphics cards in one computer.)  While my primary card was running hard and hot, its companion continued strolling along, completely unaffected.  (I'm not disappointed.  We got the second card mostly to help with rendering 3D scenes and models and for other Adobe graphics products.)

So, if you want to run SL on "Ultra" graphics settings, get the best card you can afford and give it plenty of cooling.  I don't think I'd ever do it with a laptop...I'd be afraid of second degree thigh burns.

UPDATE, August 13 --
The latest drivers, or maybe a change in LL's server code, have improved my numbers while running shadows!  Temperatures are down around 75C, power and GPU loads have dropped by half.  I am not sure what happened, but I'm happy about it!

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