Mac Pro 5.1 Double GPU (Power Supply Solutions)

Although you won't find an exact match, you could enter similar parts in a site like http://pcpartpicker.com/ to get an idea of total power consumption.

CPU and GPU will be the biggest drain, followed by hard drives (so if you have SSDs you'll be better off). I'd include 100W to cover motherboard, accessories and misc fans just to be safe.

The PSU is 980W. So you should be good.

But you can see how a dual CPU maxxed out with 7200rpm hard drives and very fast GPU could reach that limit.

the 980 ti needs two power cables connected, but the mp 5.1 motherboard only has two power connectors for video card.

When you decide to use your old video card AND the 980ti, you would need three video power sockets (which the mb does not have), or a solution with a complete second power supply. IN my opinion this is only the last step that should be done.

I have a flashed version on the 980 ti running in my mp 5.1, perfectly!

Yes, the maximum power consumption under "high-end-condition" of the 980ti is some watt above the nominal feed of the mb, but now in nearly one year i didnt see any fails, reboot, freezes. Not with all video-hungry games i installed under boot camp. But keep in mind that even with one 980ti it is slightly above specifications.

greetings from germany

Chris

ps.: have a look at http://www.macvidcards.com/ they have a wide variety from low-cost low-power up to high-end.

@Eric: it is not only the maximum power of the power unit, but the specifications of the video power connectors on the motherboard that limit power consumption of the video card on a mp 5.1.

I appreciate your idea. At this stage, we've given you enough info to make a more educated decision, and the option to choose between simplicity (1 PSU) or flexibility (2 PSU).

The key finding is that, with your config, a second PSU is not necessary. And honestly, I don't know what the power consumption of a GPU on standby is, especially if no monitor is connected (which, I assume, would be the only reason for you to power it separately).

Hi zoidb (are yo a futurama fan?),

when you decide to make the extra wiring to your main or a second psu, switching on and of the second psu to safe power will not be necessary (in my opinion).

Due to http://www.tomshardware.com/reviews/nvidia-geforce-gtx-980-ti,4164-7.html the power consumption of the 980 ti will go down to 5.12 watt in low power / idle state. So when not using or utilising the 980ti the extra money for your electric power supplier will be "peanuts".

The average power consumption is on the safe side. As tomshardware writes, none of the common stress tests will need more than 254 watt. Read the article carefully because of the 296 and 428 peaks.

greetings from germany

Chris

You may have seen this already but read http://www.macvidcards.com/do-i-need-an-additional-power-supply.html and the two links at the bottom of that page. These detail two slightly different approaches to fitting an internal PSU in the second optical bay.

Using an external PSU consists of using an external PSU and running the cable through one of the empty/unused PCIe slots on the Mac Pro and then connecting using standard PCIe power leads to the video card. Yes you would need to have the external PSU turned on before the Mac Pro.

Another approach you have not listed is that you can get an external PCIe expansion chassis which already has its own PSU built-in, this will power both a video card in the expansion chassis and the PCIe connector card. See - http://www.netstor.com.tw/_03/03_02.php?OTc as an example.

Note: The classic Mac Pro has a 980W power supply not a 1000W however this is obviously not a huge difference and many people for discussion purposes do often call it a 1000W power supply.

Personally I would go for the internal PSU approach. Looking at the two listed on the MacVidCards page I could not tell for the first one but the second one seems to automatically turn on the auxiliary PSU and would be the approach I would pic.