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Old Dec 3, 2012, 07:20 AM   #1
All Taken
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GTX 690 in a 2012 Mac Pro

Can I use SATA power to 8 pin PCI-e safely? I need 2x 8 Pin to power this card. Perhaps I can use a 6 pin from the back pane to 8 pin and use SATA power to 8 pin for the other connection?
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Old Dec 3, 2012, 08:06 AM   #2
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Can I use SATA power to 8 pin PCI-e safely? I need 2x 8 Pin to power this card. Perhaps I can use a 6 pin from the back pane to 8 pin and use SATA power to 8 pin for the other connection?
Risky in all cases.

I cant find the specs for sata power but i cant imagine it being more than 20-30W or so as that is the peak draw of many HDDs at start-up.

The 6-pin spec is 75W where-as 8-pin is 150W.

Unless Apple used a HUGE reserve factor on their traces then your playing with fire there.

Realistically, the Mac Pro on its own can provide 75x3 watts (225 W in total from PCI-E slot and 2 6-pin connectors).

Anything over that and I'd be worried about frying my 500 motherboard!! An external PSU would be a better bet.

Is it really worth it? The 670 and 7950 are both excellent cards...
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Old Dec 3, 2012, 08:09 AM   #3
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Risky in all cases.

I cant find the specs for sata power but i cant imagine it being more than 20-30W or so as that is the peak draw of many HDDs at start-up.

The 6-pin spec is 75W where-as 8-pin is 150W.

Unless Apple used a HUGE reserve factor on their traces then your playing with fire there.

Realistically, the Mac Pro on its own can provide 75x3 watts (225 W in total from PCI-E slot and 2 6-pin connectors).

Anything over that and I'd be worried about frying my 500 motherboard!! An external PSU would be a better bet.

Is it really worth it? The 670 and 7950 are both excellent cards...
Thanks,

It's worth it for me because for 500ish I can get a 690 which is about 5% slower than two 680 in SLI. Thinking Crysis 3 and beyond.
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Old Dec 3, 2012, 08:14 AM   #4
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Thanks,

It's worth it for me because for 500ish I can get a 690 which is about 5% slower than two 680 in SLI. Thinking Crysis 3 and beyond.
It also draws 300W. Which is a good 75W over the max the Mac Pro can supply.

If it is worth it for you, buy an external PSU...

The Mac Pro isn't really designed for this
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Old Dec 3, 2012, 08:20 AM   #5
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It also draws 300W. Which is a good 75W over the max the Mac Pro can supply.

If it is worth it for you, buy an external PSU...

The Mac Pro isn't really designed for this
lol that is a given but it's nice to play.
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Old Dec 3, 2012, 10:30 AM   #6
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I split the power (SATA type?) from the optical bay and used a Y splitter to connect it to the 8 pin on my overclocked PC 5870 - I have used this for many years playing games like Crysis etc without any problems. The two 6 pin connectors on the motherboard are used for the 6 pin on the 5870 and the othe one powers an Apple 5770* (mind you the latter virtually does nothing when I use the 5870).

Mind you, the GTX 690 would consume more power when maxed out but I am not sure if any game can really max it out unless you delibrately go for the most whorish settings.

I also use a Titanium X-Fi in Windows but that has no power cords.

*originally a 8800GT
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Old Dec 3, 2012, 10:54 AM   #7
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The 5770 pulls 108W max, so your only really drawing 30-40W from the SATA connector, not 75W!!
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Old Dec 3, 2012, 12:05 PM   #8
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Just get a GTX 680. It's really fast, and fits perfectly within the power budget of a Mac Pro.
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Old Dec 3, 2012, 12:07 PM   #9
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Just get a GTX 680. It's really fast, and fits perfectly within the power budget of a Mac Pro.
Nah, I want 2 GTX 680 and the GTX 690 nearly gives me that whilst using less power.

----------

Since nobody can answer adding on 2 PCI-E adapters to the power supply i'll ask something else. Anywhere in the UK I can find an internal 5.25 power supply?
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Old Dec 3, 2012, 12:19 PM   #10
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Nah, I want 2 GTX 680 and the GTX 690 nearly gives me that whilst using less power.
Okay, good luck then. The Mac Pro isn't built for 2 high-end GPUs, so your solution will be infinitely more complex than just dropping one card in. For me, the extra pain just isn't worth the hassle, especially given how powerful a single GTX 680 is.
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Old Dec 3, 2012, 12:22 PM   #11
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Okay, good luck then. The Mac Pro isn't built for 2 high-end GPUs, so your solution will be infinitely more complex than just dropping one card in. For me, the extra pain just isn't worth the hassle, especially given how powerful a single GTX 680 is.
But you're not me, this thread isn't asking what you would do.
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Old Dec 3, 2012, 12:31 PM   #12
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You are taking a big risk that I wouldn't take. That being said, I've never heard of anyone actually ruining their MP.

Personally, if I had to use that card, I'd get one of those internal PSUs that fit in the optical bay.
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Old Dec 3, 2012, 12:33 PM   #13
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You are taking a big risk that I wouldn't take. That being said, I've never heard of anyone actually ruining their MP.

Personally, if I had to use that card, I'd get one of those internal PSUs that fit in the optical bay.
That's the plan just looking for a reliable Graphics PSU.
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Old Dec 3, 2012, 12:52 PM   #14
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But you're not me, this thread isn't asking what you would do.
Right, but I'm free to give my advice and recommendations, which I have now done. I wouldn't risk an already expensive Mac Pro system in order to power a second high-end card.

I believe someone linked a small power supply that fits into a DVD drive slot, that might be a good option for you.
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Old Dec 3, 2012, 01:08 PM   #15
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Right, but I'm free to give my advice and recommendations, which I have now done. I wouldn't risk an already expensive Mac Pro system in order to power a second high-end card.

I believe someone linked a small power supply that fits into a DVD drive slot, that might be a good option for you.
Dude, stop rewriting your first statement in another way. The air of caution is already in place. I know the risks and don't need you to tell me that you wouldn't risk it etc etc. I just wanted straight answers tbh. If I start a new thread asking if it's risky then you can assume I don't know about the risk involved and by all means impart your knowledge.
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Old Dec 3, 2012, 01:17 PM   #16
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Dude, stop rewriting your first statement in another way. The air of caution is already in place. I know the risks and don't need you to tell me that you wouldn't risk it etc etc. I just wanted straight answers tbh. If I start a new thread asking if it's risky then you can assume I don't know about the risk involved and by all means impart your knowledge.
Keep calm, Asgorath is ine if the guys that know best how to fit a high-end GPU in the Mac Pro.
Now keep calm and buy a bloody regular 600W PSU and place it behind the Mac Pro.
5.25'' PSU's aren't powerful enough for a 690 or two 680s.
Google knows it all.
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Old Dec 3, 2012, 01:20 PM   #17
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Keep calm, Asgorath is ine if the guys that know best how to fit a high-end GPU in the Mac Pro.
Now keep calm and buy a bloody regular 600W PSU and place it behind the Mac Pro.
5.25'' PSU's aren't powerful enough for a 690 or two 680s.
Google knows it all.
Fantastic thank you for giving me the answer. I'm not really wanting an outside box. The internal GPU PSU is an idea I can get on board with and have found one that offers 450w with 2 8 pin cables - internal 5.25. Any good?

I'm not angry and appreciate any constructive feedback but the risks to me are known and are obvious to most. Harping on about them really doesn't do anything constructive.

If 450w is not enough, overhead etc taken into account with a GTX 690 could somebody provide feedback on the use of a 6 pin to 8 pin wire from one of the Mac Pro connectors combined an 8pin wire from the 450w PSU. In effect I have The 5.25 bay PSU providing half the power draw and the Mac itself providing the other 50%. Can the Mac Pro provide that sort of power on one 6 pin to 8 pin connection safely?
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Old Dec 3, 2012, 01:46 PM   #18
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Fantastic thank you for giving me the answer. I'm not really wanting an outside box. The internal GPU PSU is an idea I can get on board with and have found one that offers 450w with 2 8 pin cables - internal 5.25. Any good?

I'm not angry and appreciate any constructive feedback but the risks to me are known and are obvious to most. Harping on about them really doesn't do anything constructive.

If 450w is not enough, overhead etc taken into account with a GTX 690 could somebody provide feedback on the use of a 6 pin to 8 pin wire from one of the Mac Pro connectors combined an 8pin wire from the 450w PSU. In effect I have The 5.25 bay PSU providing half the power draw and the Mac itself providing the other 50%. Can the Mac Pro provide that sort of power on one 6 pin to 8 pin connection safely?
Here's an idea:
Use a Y-cable to take the two ports given by the Mac Pro for one 8-pin, and plug the other one into your FSP Booster (that's the PSU you mentioned, correct?). This should work.
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Old Dec 3, 2012, 02:06 PM   #19
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Here's an idea:
Use a Y-cable to take the two ports given by the Mac Pro for one 8-pin, and plug the other one into your FSP Booster (that's the PSU you mentioned, correct?). This should work.
Can I use a Y splitter - 6 pin plus 6 pin safely?
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Old Dec 3, 2012, 02:21 PM   #20
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I'm not 100% sure but:

If one 6pin connector can take 75W, and a 8pin can take 150W -> 2x 6pin can take 150W, so you seem to be safe?
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Old Dec 3, 2012, 02:45 PM   #21
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Dude, stop rewriting your first statement in another way. The air of caution is already in place. I know the risks and don't need you to tell me that you wouldn't risk it etc etc. I just wanted straight answers tbh. If I start a new thread asking if it's risky then you can assume I don't know about the risk involved and by all means impart your knowledge.
You clearly weren't here 6 months ago when every week there'd be a new thread about "ZOMG please help me get a GTX 580 working in my Mac Pro!!!1!11!". If you know the risks and want to proceed anyway, that's great. I'm always a little wary of solutions that require an external power supply since it takes a lot of effort and a lot of modifications to ensure they are daisy-chained correctly, and even then I'm not sure you can guarantee that the power supplies are in sync with each other (though hopefully cards are fairly tolerant of that these days). Given that if something goes wrong, you can and will destroy the card and/or your entire system, I think it's quite reasonable that the risks be brought up so that others are aware of them, even if you know exactly what you're doing.

FWIW there's a guide on how to rig the second power supply, which you'll probably want to take a look at. Edit: Looks like there's one for internal power supplies as well:

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As far as external / internal power, here are 2 tutorials:

External:
http://forums.macrumors.com/showthread.php?t=1460429

Internal:
http://forums.macrumors.com/showthread.php?t=1076970
Quote:
I'm not angry and appreciate any constructive feedback but the risks to me are known and are obvious to most. Harping on about them really doesn't do anything constructive.
I certainly wouldn't classify the risks as obvious based on the history of posts/threads on this forum, though hopefully my FAQ thread has helped in that regard.

Either way, I'm simply trying to help and confirm that you know what you're getting yourself into.
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Old Dec 3, 2012, 02:56 PM   #22
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Thanks,

It's worth it for me because for 500ish I can get a 690 which is about 5% slower than two 680 in SLI. Thinking Crysis 3 and beyond.
you have a 2012 mac pro and you are getting that card.... for gaming? Despite all the risks??

I have a bridge to sell you sir....
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Old Dec 3, 2012, 02:59 PM   #23
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you have a 2012 mac pro and you are getting that card.... for gaming? Despite all the risks??

I have a bridge to sell you sir....
Haha, I have a love of OS X and can't spare the desk for a gaming rig.
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Old Dec 3, 2012, 03:00 PM   #24
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The 5770 pulls 108W max, so your only really drawing 30-40W from the SATA connector, not 75W!!
The SATA connector powers the 8 pin on my 5870 which totals somewhere around 200W if memory serves me correct, I know, still a farcry from the mighty 690.

I think the 690 was designed with some headroom for overclocking so I would be surprised if it does consume 300 W.
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Old Dec 3, 2012, 03:01 PM   #25
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You clearly weren't here 6 months ago when every week there'd be a new thread about "ZOMG please help me get a GTX 580 working in my Mac Pro!!!1!11!". If you know the risks and want to proceed anyway, that's great. I'm always a little wary of solutions that require an external power supply since it takes a lot of effort and a lot of modifications to ensure they are daisy-chained correctly, and even then I'm not sure you can guarantee that the power supplies are in sync with each other (though hopefully cards are fairly tolerant of that these days). Given that if something goes wrong, you can and will destroy the card and/or your entire system, I think it's quite reasonable that the risks be brought up so that others are aware of them, even if you know exactly what you're doing.

FWIW there's a guide on how to rig the second power supply, which you'll probably want to take a look at. Edit: Looks like there's one for internal power supplies as well:





I certainly wouldn't classify the risks as obvious based on the history of posts/threads on this forum, though hopefully my FAQ thread has helped in that regard.

Either way, I'm simply trying to help and confirm that you know what you're getting yourself into.
Apologies if I was bit harsh earlier I just have had a lot of similar replies when asking these sorts of questions. I know it's just good advice but it's something I feel people should know if they are messing with this stuff anyway. The links are very much appreciated, any comment on the safety of using a Y splitter to 8 pin on the 6pin outs of the Mac Pro?
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