A posting on another forum stated that some of the earlier Nvidia drivers are faster than later ones, though I don't have link to that post (probably on Einstein). So I tried it out on my GTX 970 on GPUGrid, going back from 361.43 (the first of the CUDA 8 drivers) to 359.06 (the last of the CUDA 7.5 drivers). I tried to find the most comparable work units, but the trend is clear whether you get an exact match or not (Win7 64-bit in all cases):

361.43 (CUDA 8) driver:
e7s29_e2s13p0f526-GERARD_CXCL12VOLK_12998741_2-0-1-RND3569_1
13.85 hours (44% CPU utilization)

359.06 (CUDA 7.5) driver:
e12s19_e7s8p0f14-GERARD_CXCL12VOLK_12998741_1-0-1-RND7922_0
12.59 hours (31% CPU utilization)

The conclusion is that the older drivers produce both faster results and lower CPU utilization. (This card is supported by a full core of an i5-3550, so the numbers will be somewhat different on virtual cores.)

While I was at it, I compared the efficiency (work units/day/watt) of the GTX 970 to a GTX 960. Somewhat to my surprise, they are virtually the same, with the GTX 960 squeaking out maybe a 2 or 3 percent gain, but almost too small to measure reliably.

Very interesting. What about the "CUDA 8" drivers that are newer, perhaps more mature?
How about even older drivers. Any ideas on those vs. 7.5?

Good questions, but my experience is that the CUDA drivers are pretty stable once they are released, and the later driver versions just optimize gaming performance. I don't do games, and this is on a dedicated machine anyway, so that does not matter.

You are more than welcome to try it also, and post back.

By the way, I measured power using the TDP% in GPU-Z, and the CPU% in BoincTasks.

Drivers become bloated with patches and it slows some apps down. Operating systems get bloated in a similar way.

Same here: 362.00
41203 s for 280,650 credit WUs (6 samples)

359.06
38818 s for 280,650 credit WUs (3 samples) MrS

The difference observed by Jim1348 was 10% while the difference observed by ETA was 2%, so perhaps subsequent drivers (ETA's being slightly newer) or different setups change things.

The latest apps hear are CUDA 6.5 so any drivers that support 6.5 should suffice (unless there has been reported issues).

Whatever the route I don't see why NV would dev for older products, so I would not expect any performance gain from CUDA 8 for 28nm GTX cards

Jim, thanks for this heads up. Switching to the 359.06 drivers has allowed one of my machines to make the 24 hour deadline for 7 of the last 11 WUs (sometimes by as little as 2.5 minutes). Previously it was missing all the 50% bonus times after "upgrading" to 362 drivers. I'm currently not having warm fuzzy feelings about nvidia.

Switching to the 359.06 drivers has allowed one of my machines to make the 24 hour deadline for 7 of the last 11 WUs (sometimes by as little as 2.5 minutes). Previously it was missing all the 50% bonus times after "upgrading" to 362 drivers. I'm currently not having warm fuzzy feelings about nvidia.

Jim, thanks for this heads up. Switching to the 359.06 drivers has allowed one of my machines to make the 24 hour deadline for 7 of the last 11 WUs (sometimes by as little as 2.5 minutes). Previously it was missing all the 50% bonus times after "upgrading" to 362 drivers. I'm currently not having warm fuzzy feelings about nvidia.

Switching to the 359.06 drivers has allowed one of my machines to make the 24 hour deadline for 7 of the last 11 WUs (sometimes by as little as 2.5 minutes). Previously it was missing all the 50% bonus times after "upgrading" to 362 drivers. I'm currently not having warm fuzzy feelings about nvidia.

could you please let us know which GPU and which OS you talk about in this case?

I am asking because I seem to be in a very similar situation with one my PCs.
Thanks in advance.

Maybe you should ALL think about contribution rather than speed and "beggar thy neighbour"

As luck would have it, my GTX 970 machine crashed yesterday for no good reason and would not boot at all. The SSD (a Samsung 850 EVO) even disappeared until I re-enabled it in the BIOS. But after completely wiping it out with a secure erase, it appeared to be OK. Rather than re-installing Win7 64-bit, I decided to go with Ubuntu 16.04; the second of my machines to be converted.

The first GPU work unit was a GERARD_CXCL12VOLKX. That may not be exactly comparable to the one I did on Windows with the CUDA 7.5 driver, but at 11.2 hours, a 12% difference, it shows that things are heading in the right direction. I would not bother with that except for the crash, but it was a nice incentive.

Maybe you should ALL think about contribution rather than speed and "beggar thy neighbour"

The 6.12 app upgrade from 6.05 was similar, 5 1/2 years ago, and I recall successive driver 'updates' also slowed my GT240's down bit by bit.