You need a second power supply to run a 2nd video card, or get a 2nd video card that doesn't require additional power like a GTX120. There are multiple threads on how to rig an external and even a second internal PSU
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My Review of GTX 670 in OS X and Win7!
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You need a second power supply to run a 2nd video card, or get a 2nd video card that doesn't require additional power like a GTX120. There are multiple threads on how to rig an external and even a second internal PSU
Based on the information from this thread and elsewhere and some of my own testing, I've published a how-to over at Mac Gamer.
Another issue with having an AMD in the computer: the PhysX option in Borderlands 2 (and apparently other games) is turned off. You can hack the game to turn it back on (google is your friend), but I've had stability issues with that.
Could you provide a link, please. And what other graphics cards that are supported by Mac Pro don't require additional power, cause the GTX120 isn't available anymore. Sorry for noobish questions.
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As far as external / internal power, here are 2 tutorials:
External:
https://forums.macrumors.com/threads/1460429/
Internal:
https://forums.macrumors.com/threads/1076970/
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Get a SATA to molex connector. I'm powering one of my cards from my drive bay using a SATA to molex cord.
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Interesting. I did not know this. Maybe I'll unplug my 5870 next time I'm in windows and try Batman Arkham City and see if there's any new PhysX options for me to turn on.
Be careful about this, as far as I know the SATA power cable does not provide the full 75W that the card expects. I'll see if I can dig up the actual numbers.
I've been powering two cards in my Mac Pro for quite a few years now.
I started back when Cindori started flashing the PC ATI 4890's to work in the Mac Pro. Back then in my 1,1 I had both a Mac version of a 4870 and a PC 4890 on the go at the same time. One was powered by the regular power cables in the computer, and the other was powered from the spare power cord in the optical drive bay.
Cindori recommended doing this to have both cards running. There were also several threads on it at the time.
After a few years I switched out the 4890 with a Mac version of a 5870. I ran both the Mac 4870 and 5870 in my Mac Pro 1,1. Again, one card was powered from the traditional method - the supplied power cables - and the other was powered from the optical drive bay.
I had been using the computer with a dual card set up since 2009 and never had a single problem.
Now I have a Mac Pro 5,1 and I am using the same method, only this time with the Mac 5870 and a PC GTX 670. I can't imagine the power comsumption of these two new cards is more than the 4870 and 4890 I was running at one point together.
Thoughts?
I started back when Cindori started flashing the PC ATI 4890's to work in the Mac Pro. Back then in my 1,1 I had both a Mac version of a 4870 and a PC 4890 on the go at the same time. One was powered by the regular power cables in the computer, and the other was powered from the spare power cord in the optical drive bay.
Cindori recommended doing this to have both cards running. There were also several threads on it at the time.
After a few years I switched out the 4890 with a Mac version of a 5870. I ran both the Mac 4870 and 5870 in my Mac Pro 1,1. Again, one card was powered from the traditional method - the supplied power cables - and the other was powered from the optical drive bay.
I had been using the computer with a dual card set up since 2009 and never had a single problem.
Now I have a Mac Pro 5,1 and I am using the same method, only this time with the Mac 5870 and a PC GTX 670. I can't imagine the power comsumption of these two new cards is more than the 4870 and 4890 I was running at one point together.
Thoughts?
Well the good news is that using power from the drive bay should not overload the tracers on the motherboard, so it is technically "safe" for your Mobo. The only issue is whether or not the 5.25 drive bay cable will allow you to draw enough amps without triggering a shut-down or having voltage variability.
Say you have a GTX670 with an 8 pin and a 6 pin -- that can draw ~250 watts from the 6/8 pin plugs, in addition to the ~75 watts off the mobo. If you are pulling that through a single 12 volt lead coming from the drive bay (especially in the new macs where you have to "adapt" it from the SATA power plug), that may make the wires a bit warm/melty, even if the 12v PSU rail is within tolerances.
Does anyone know how many 12v rails the Mac Pro PSU has??
Anyways, regardless, I'd stop doing what you're doing.
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I think you may be able to disable it through software (find the 5870 in device manager and disable it).
I manually enabled physx in borderlands 2 though the game GUI wouldn't let me (you edit some .ini file). On the medium/high setting it crashes the game, low setting works fine even with the 5870 in place
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I am using the same wires as I have for the past 3 years. Haven't noticed any of them being overly melty as of yet. Never had a shut down or any sort of a power surge either.
I am not too worried about it. Chances are everything will be alright.
Thanks tho.
The GTX 670 stock wires all seemed to be 6 pin too. Didn't notice any 8 pins but I will take another look.
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Here's some links from the old threads I used back in the day about using the power from the drive bay:
https://forums.macrumors.com/threads/713428/
https://forums.macrumors.com/threads/877441/
https://forums.macrumors.com/threads/418279/
The GTX 670 -- at least gigabytes -- can consume 325 watts. The 5870 consumes even more than that (as I note earlier in this thread.
The 4870/4890... well take a look:
As you can see, they consume a lot less. So yes, these new cards (GTX 670 + 5870) consume significantly more power than the 4870/4890 that you have had "no problems with". I would highly recommend re-examining your setup if you do indeed run either one of these cards off a single 12V lead coming from the drive bay.
I don't know if you'll ever have any issues running this way, but you're definitely pushing the tolerances of your cabling. Even if you have a "reference" GTX 670 with only Two 6-pin plugs, the card is expecting FOUR 12v leads with a total rated capacity of 150 watts. You're potentially shoving that amount of wattage through only 1 lead.
18 gauge wire --JUST THE WIRE (connectors are less)-- is only rated for 7 amps. You're potentially running 12.5 amps through it. [Edit: just found out that in the case of light fixtures in homes, running more than 6 (six) amps through an 18 gauge wire is actually against the law]
Likely the consequences will be voltage variability and heat generation during high-load. It may not lead to fire or melting or anything dramatic, but it's very possible you'll lead to instability.
Now. If you have a Non-reference GTX 670 with an 8 pin plug and a 6 pin plug, that's got a lot more potential. 8 pin plugs are rated for up to 225Watts (18 amps) by themselves. You may be okay if you don't manually overclock, but I wouldn't risk it.
Food for thought.
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Thank you for the information. I'll take some pictures in a few minutes to show you what cords/wires I am using exactly.
I apologize if I seemed rude before; I'm not electrically inclined in the slightest, and I was only following steps that worked before.
Yep, that's pretty much how I assumed you had it setup. At least it looks like you're using a reference card GTX670 (lower power than the others). The greatest resistance is going to be right on your SATA connector.
Those three tiny 12 volt squares of metal have to handle up to 12 amps in your setup. They are rated for 1.5 amps each according to this--totalling 4.5 amps. That's only 54 watts, when it should be 150 watts
Again, it probably wont break any of the expensive components (like the motherboard or PSU... provided Apple isn't using single rail...). However, potentially you could have some issues with damage to the wires, lower framerates, and software instability.
If it works for everything you're using it for and you're okay with the risk, I guess there's no reason to change anything. Just don't play Battlefield 3 on max or that little connector is going to be very upset with you
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Thanks for the mention over there. I'm glad someone is putting this stuff out there, I hope NVidia makes a mint for all the options they've brought to us. The more Mac Pro users who buy their stuff, the more drivers they'll make (maybe some EFI firmware too!).
Yep, that's pretty much how I assumed you had it setup. At least it looks like you're using a reference card GTX670 (lower power than the others). The greatest resistance is going to be right on your SATA connector.
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Those three tiny 12 volt squares of metal have to handle up to 12 amps in your setup. They are rated for 1.5 amps each according to this--totalling 4.5 amps. That's only 54 watts, when it should be 150 watts
Again, it probably wont break any of the expensive components (like the motherboard or PSU... provided Apple isn't using single rail...). However, potentially you could have some issues with damage to the wires, lower framerates, and software instability.
If it works for everything you're using it for and you're okay with the risk, I guess there's no reason to change anything. Just don't play Battlefield 3 on max or that little connector is going to be very upset with you
Thank you again for the information. What I might do then is put my GTX 670 in the PCI card slot 1 and move my 5870 to slot 2. That way the GTX 670 will be powered directly from the motherboard for all the heavy lifting. I will attach my two main monitors to it. I'll only attach my Wacom Cintiq to the 5870 powered by the SATA then. Should be okay for Battlefield 3 on Max then
so i got my gtx 670
evga 2gb FTW to be precise. Gonna install it tonight, first gotta upgrade from snow leopard to mountain lion, then it's on. quick question: should I put this baby in the 2nd slot? I'm bouncing my old 8800gt altogether so the 670 will be the only gfx card in there, long term is that a better option for airflow etc?
Cant wait to test this thing out!
Dave
evga 2gb FTW to be precise. Gonna install it tonight, first gotta upgrade from snow leopard to mountain lion, then it's on. quick question: should I put this baby in the 2nd slot? I'm bouncing my old 8800gt altogether so the 670 will be the only gfx card in there, long term is that a better option for airflow etc?
Cant wait to test this thing out!
Dave
Thank you again for the information. What I might do then is put my GTX 670 in the PCI card slot 1 and move my 5870 to slot 2. That way the GTX 670 will be powered directly from the motherboard for all the heavy lifting. I will attach my two main monitors to it. I'll only attach my Wacom Cintiq to the 5870 powered by the SATA then. Should be okay for Battlefield 3 on Max then
Dude, you are asking for a world full of hurt with that mess of adapters.
Every adapter you add is adding to the resistance, if you insist on powering things this way, solder the wires yourself and cut 15 inches of thin cheap steel wire out of there.
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Here is something to think abbout, I just pulled a DVR-105 from my Mac Pro. It claims to draw a max of .6A at 12V. So the DVD drive draws 7.2 Watts. So two if them draw 15 Watts. I doubt Apple planed on drives drawing more than 10 Watts. And you are drawing 150 Watts through the same power system. Really think about that.
Before you posted I actually took the 5870 out, as well as a bunch of the Molex connectors. I replaced the card with the 5770, which using a single six pin connector.
I'm looking into adding an additional PSU, but the whole process seems rather complicated with soldering or splicing, both of which I am sorry to say, I have no experience doing.
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Is it possible to buy an external PSU, plug it into the wall, run power cords from it to the GPU...and then manually switch the PSU on or off depending on the need of the second GPU?
Yes, you just need to shove a paperclip or a wire into the connector (Green to black):
If I put the computer to sleep can I leave the external PSU running or will I have to turn it on and off each time?
EDIT: Thanks again for your help.
EDIT: Thanks again for your help.
