Thanks to habitullence for triggering some of my neurons to fire.
Habitullence recently brought to my attention this video on dual Titans vs dual 780s -
http://www.youtube.com/watch?v=7rS88DG9TJo and asked for my take on their conclusions.
My takes are:
Those results are for gaming w/SLI configurations. If I were building a gaming rig for single or SLI configuration, I'd get 780s over Titans (or as suggested,
below, I'd wait just a bit). But gaming won't pay my bills.
For CUDA 3d rendering in OctaneRender one should not use SLI. Using SLI only impairs the process [
http://render.otoy.com/faqs.php - "Does Octane Render take advantage of SLI? No, but it can use multiple video cards for rendering (see above). It is also recommended to disable the SLI option in your Nvidia control panel to maximize Octane's rendering performance." ].
The 780s, at stock, are clocked higher than regular Titans [the non-EVGA SuperClocked ("OC") versions]. But if a gamer overclocked two regular Titans to run at the same speed as the two 780s at factory (a feat easily doable in Windows with regular Titans, then those Titans would most likely excel at those gaming oriented benchmarks. One could spring for the EVGA "OC" version to get a more powerful Titan card if he/she didn't want to do any overclocking him/herself or was using a Mac Pro. All of my Titans are the EVGA "OC" versions and I have over 300 MHz of overclocking headroom still left. The Titan, at stock, has twice the amount of ram as a 780 (and about eight times the double precision floating point peak performance of the 780s when run in Windows if one uses Nvidia Control Panel to release that ability; and "no" you can't do that with a 780). Ram size and double precision increased capability are the two main reasons for Nvidia's Titan vs. 780 pricing differential. For 3d rendering a Titan can render a scene so large with so many objects and textures as to cause a 780 to choke, i.e., the 780 couldn't render the scene at all. And with the additional double precision floating point peak performance, a Titan has the potential to render that larger/more complex scene extremely fast.
However, if you haven't already purchased GPGPUs cards, you might want to wait for about two months. Nvidia has hinted that it may soon be releasing a $1,000ish real monster - the GTX 790 (that's dual 780s) [
http://videocardz.com/nvidia/geforce-700/geforce-gtx-790 ]. But note - it may require dual eight pin power connectors. If the specs are as shown by
videocardz, then this is the card (with 4,992 CUDA cores running at stock speeds of 1,100/1,150 MHz) that I might surely recommend over any Titan1 (with 2,688 CUDA cores running at stock speeds of 837/876 MHz for the regular version and at stock speeds of 876/928 MHz for the EVGA "OC" version). The 780 has 2,304 CUDA cores running at stock speeds of 863/900 MHz. The 780's memory bus is the same as the Titan's - 384-bit with a memory bandwidth of 288 GB/sec and an effective memory clock of 6,008 MHz. The 790 is projected to have 6 gigs of ram and a 768-bit memory bus, but an effective memory clock of only 6,000 MHz, 8 MHz lower than that of the 780 and the Titan. Ultimate configuration of that memory in the 790 will matter greatly - such as is that per card or total for both cards. The latter, which is more likely the case, would just be the same as for a single 780. Hopefully, there's a Titan2 waiting in the wings. What if the Titan2 is the GTX version of the recently announced Tesla K40(X) with a GK180 GPU [
http://videocardz.com/46388/nvidia-launch-tesla-k40-atlas-gk180-gpu ] just as the Titan1 is the GTX version of the Telsa K20(X). That would mean that the Titan GK180 might be a more specially binned GK110 chip, with 12 gigs of ram, 2,880 CUDA cores, higher core speeds, higher memory bandwidth and thus greater single and double precision floating point performance, all while still maintaining the same TDP and $1,000 price tag.
My guess is that current 780 and Titan1 prices may soon let go of the handles on top of the price sliding board. But Titan1s have been so limited in sales quantities that the effect on them will be extremely limited. Moreover, if there's no Titan2, Titan1'll still have that ram size and double precision floating point advantages to act as glue on their backsides or, at least, to soften their little fall.
Isn't Nvidia's battle with AMD wonderful. Competition - I love it.