NVIDIA GF100 & Friends speculation

Let me just pose this question then: if one were to take a GTX 480 and run the fan @ 100%, perhaps bringing the loaded temperature down from 95 degrees C to say 75 degrees C, is it possible this would cause a measurable reduction in power usage, aside from the obvious increase in power draw by the fan itself?

 

yes. Most likely you would have a measurable difference in power from a ~20c operating differential.

 

Thanks!

 

To put that into context - at around about operating temps, IIRC, we saw roughly a correlation of ~1W to 1 degree on Cypress.

 

I was just teasing the guy for his statement.

Joking aside, higher temperatures should affect leakage. Undoped Si between transistors, p-n junctions, and even the gate insulator increases in conductivity, and higher temperature increases tunnelling current, too. I don't think the resistance of the doped areas make much difference to power consumption.

Thanks, Dave, for the quantitative data.

 

It's very easy to see in HardOCP's power/noise video (with sound on, so you can hear his temperature readings): http://hardocp.com/article/2010/03/26/nvidia_fermi_gtx_470_480_sli_review/7
Furmark should be running with constant load, but still the power consumption goes from 435W at start to 450@75C to 483@95C

 

That would imply 33w for 20C Almost 2w/C.

 

But that's power draw measured at the AC source, so losses/efficiency/thermal variance of the rest of the system has to be factored into that reading.

 

Right, I was thinking that might be the case, but I wasn't sure.

 

Plus increase in fan speed which adds to that as well.

But I did several tests on my Cypress when First got my card and I can confirm that what Dave said is very correct. +1C=+1W at full load for stock HD5870 between 70C and 85C at least.

 

Excellent. Thanks for quantifying that for us, Wavey.

 

That entirely depends on the material. Some have a negative temperature coefficient (NTC) others positive (PTC).

 

Let's not forget it's also a TWIMTBP game as well

 

Also apparently ATI didn't get access to the final game code either.

http://hardforum.com/showpost.php?p=1035518165&postcount=27

I just can't fathom why they would purposely not give ATI access to the final code to tweak their drivers, if TWIMTBP is just supposed to be Nvidia offering support like they claim.

 

As far as I know, ATI doesn't have a comparable developer relations program, so they would hardly have reason to show ATI their code. ATI might just say, "That's nice. Why are you showing this to us?"

 

Good point! That'd also correspond with the OC results we were getting.

 

HT4U did some measurements about this over here:
http://ht4u.net/reviews/2009/leistungsaufnahme_graka/index9.php

 

The difference is that nVidia is actively reaching out to developers, in effect saying, "Let us help you with that. We can make your game run faster!" And also bear in mind that nVidia's developer relations program is highly unlikely to exclude optimizations that would also help ATI hardware, thus the TWIMTBP program likely improves game performance for both IVH's, but obviously the program's main focus is going to be nVidia hardware, not least because nVidia's support surely knows much more about nVidia hardware than ATI hardware.

 

Wow, I was wondering why my entire PC draws south of 250W under load given TDPs of both Cypress and Yorkfield (both OC'ed)! So water cooling is power efficient as well !