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macrumors newbie
Original poster
May 15, 2013
Hi everybody
just to report the installation of an EVGA GTX 980 Ti SC+ in my cMP 4,1 (firmware upgraded 5,1).
Up to now, it works perfectly without an external PS (use of a 6pin to 8pin adapter) in my fully loaded mac Pro :
- W3690 3,46 GHz
- 24 Gb memory,
- 4 magnetic HD
- 2 SSD on sata-2 connections in optical bay
- 2x velocity x2 with 2 SSD each (so 4 SSD in sata-3 via the 2x velocity solo x2 + 2 SSD on sata-2)
- USB3 inatek PCI card (4 USB3)
- EVGA GTX 980 Ti SC+ with 2 screens (on PCIE 16 lanes slot)

I was a bit worried about power consumption but it seems that it is fine on OsX el capitan 10.11.4 with latest nvidia drivers and on Bootcamp Windows 10 with latest drivers

no crash or artifacts on all the games I played up to now on Windows 10. Most of the games are playing at 60 FPS (with V-sync) on 2560x1440 60 Hz with max settings. The card with 1102/1190 MHz gpu clock specs, shows actual 1304 Mhz in games at full load, with around 79 °C and 40-50% fan speed. Very quiet on idle (fans are not spinning) and still quiet at 50% fan speed. A really worth upgrade from my EVGA gtx 970 FTW.

the card is specified to require 275 W which is theoretically greater than what is available from the PCI-e (75 W) and the 2 on board 6-pin connector (2 x75 W). I was prepared to power the card by feeding the 8pin connector through the 2 on board 6 pin connectors with a splitter AND another splitter to take power from the SATA-2 connectors in the optical bay to feed the on card 6pin connector (theoretical 75+75+75+25+25 Watts ?). But it seems this is ok. And i can keep my 4 SSDs in the optical bay. i guess that means that the macpro PS can provide with the PCI-e and the 2 6 pin on board connection more than the 225 W it seems it is specified for. Of course, I read that this way of feeding a graphic card is a little bit risky because the motherboard may be damaged by too much current draws (over 225 W specified). But there are no reports in my knowledge of such damages.

I did not do tests in CUDA yet. OpenCL is working (at least in furmark scala seen bench).

I bought the card mainly for gaming in windows and I'm fully satisfied !

Now that the 1000 nvidia series is out (but not yet supported in OsX) GTX980 Ti are more affordable and in my opinion a great and worth upgrade for our cMP

It was a bit tricky to get the double boot OSX / Windows10 (especially because of EFI boot and the no-boot screen on OSX) but I solved the problem with BOOTCHAMP which enables to EFI-reboot the macPro on Windows 10 from osX.


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macrumors 6502
May 4, 2011
Thanks for sharing - could you please run some benchmarks? Such Luxmark 3.1, Valley & Heaven, thanks.


macrumors newbie
Original poster
May 15, 2013
on OSX el capitan 10.11.4, nvidia webdriver 346.03.03f01
Luxmark 2.1 Sala scene, Gpu & accelerators only : 3396
Heaven 4.0, OpenGL, 1920x1080 windowed, High preset, Tesselation OFF : 2311, 91.7 FPS avg, min11.3 FPS max 184 FPS
Valley 1.0, OpenGL, 1600x900, 8xAA windowed, extreme preset, 2489 , 59.5 FPS avg, 23.8 FPS MIN, 97.6 FPS Max

more to come also on windows

best regards
[doublepost=1470433144][/doublepost]luxmark 3.1 luxball HDR scene, Gpu & accelerators only, 16847


macrumors newbie
Original poster
May 15, 2013
Difficult to estimate. Mine is the already a little bit aoverclocked and may draw much power than reference card and my Macpro is fully loaded.

I only use the 6 and 8 pin connectors through the 2 6 pin of the MacPro. No additional power feeds (but I have an adapater to connect the 2 SATA connectors in case)

That may explain what I observed after 2 weeks of use :
- on osx, everithing's fine. I do not play hardcore games, just photo and video editing
- on W10 : I had one shut-down of the computer which scared me. But no harm after reboot
This shut down occured at launch of a game (batman arkham Knight)
the card was idle with clock at 135 MHz and T at 48 °C
So i do not think it is power related

I played heavy games at 60 fps Vsync at extreme or ultra settings, looking at clock, T, TDP online
The card never crashed the computer under these heavt loads : T around 80°C, TDP around 70%, fan speed around 50%.

VR in 4K may have more demand of power than my use.

I may say give a try like me, monitoring gpu parameters.

To be safe, of course, and if you can, connect the 2 6 pin of the motherborad to the 8 pin of the card and the 2 SATA to the 6 pin. Quite sure the additional 50W will be sufficient (for me I like my 6 SSDs and would like not to lose 2 for powering the card).

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