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slughead

macrumors 68040
Original poster
Apr 28, 2004
3,107
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I don't have a lot to say here. Basically some tips and tricks. Basically: Yes, you can just throw a GTX 670 into your mac pro running 10.8 (or, I guess 10.7 with the NVidia drivers) and as soon as the login screen shows up, It Just Works.

A couple of things: first off, I got the 2GB version, any more than 2GB and you have to hack the OpenCl drivers to use that feature in Adobe / Apple's apps that use GPU acceleration help. You can download the CUDA drivers off of NVidia's website but with Mountain Lion, you need *NO* additional drivers to boot and start using the card.

I chose the 670 because it was Tom Hardware's "best card for the $$$" in that price range ($400). It is stupidly fast and has some extremely good cards out there.

Which Model?:

There are like 20 GTX 670's out there... kind of makes it complicated to decide. I've been using Toms Hardware guide for years to build PCs, so I relied heavily on this article and ultimately chose this card:

14-125-423-TS


So which one to choose? I chose the GIGABYTE GV-N670OC-2GD based on several reviews. This thing is One of the fastest cards because of an overclock chip (automatically overclocks when the card is cool... which it always is), but not the fastest (others can OC higher). It is also one of the quietest/coolest but not the quietest/coolest. I was basically looking for a balance between speed and temperature. Price is not a big factor because most of these cost about the same (unless they're the 4GB model). This model has 3 fans and is about 11 inches long--fits just fine in the Mac Pro, which tolerates even 12 inch cards. The thing really is amazingly quiet. Your Mac Pro fan will likely be louder.

A couple caveats:

Power: The stock GTX670 with two 6 pin power inputs will run perfectly off of the two 6 pin outlets on the motherboard, however most cards are not stock cards. Some GTX670's have an 8 pin plug which may require an adapter, but be careful as this will give the card the potential to damage your motherboard. However, provided you do not manually overclock the Gigabyte card mentioned above (automatic overclocking is fine), you will be well under the limitations of the computer (note: going over the limit is a bad idea). For other GTX 670's, check the reviews for power consumption information. [Edit: There is some trepidation about this, however as you can see in this post, the 5870 (shipped by Apple with the Mac Pro) uses more power than this card. GTX670 is particularly efficient. As long as you don't manually overclock the card, it will stay within reasonable amperage parameters even when using the automatic overclock chip. Other GTX670's with automatic overclocking may draw more wattage, so check the reviews first.] However, you need to buy a 6 pin to 8 pin adapter in order to do this. I chose to use my external PSU I rigged up for my second 6870 card. Why did I do this? Because I had it in place already and because I wanted to leave in a second video card for reasons below.

Edit:

The 8 pin is for overclocking purposes. If you don't overclock, it is highly doubtful that you need it. GTX670 that has 8 pin are using the GTX680 PCB. The chip itself is fine with 2x6pin and the extra components on the PCB is unlikely to make a huge difference. Most GTX670 that come on GTX680 PCB are overclocked but not enough to increase power usage significantly. It is when you dial up all the settings in the overclock utilities (EVGA PrecisionX for example) that you will see a difference.

Edit2: Later in this thread, "Redneck" suggests powering your 2nd card off a single 12v lead coming from the 5.25" bay. Please do not attempt this. I break it down here why that's a really bad idea.

Boot Screens: No, you can't see boot screens with this... not until someone finds a firmware to flash it with. Personally, I like having the boot screen since I like to boot into windows a lot and use the boot selector (hold option while booting). Consequently, I have a second video card.

Positioning: I keep it in slot 2 because I have two 16x PCIe ports in my Mac Pro 5,1. The 2nd slot has better ventilation and also I read on one of these forums that the behavior is better if you have your "primary" card in slot 1 in OS X.

Second card issues: I have a flashed 6870 as my slot 1 card so I can see boot screens. Windows apparently has a huge problem running AMD and Nvidia cards at the same time... basically I uninstalled my catalyst (AMD) drivers and everything works great. However, the 6870 is probably not very useful for gaming now without those drivers installed. Basically, when I initially installed the 670, the screen remained black in Windows until I uninstalled the AMD drivers. I've had no issues in OS X.

Technical issues summary: After arranging supplemental power and after fixing that windows issue, essentially I've had no issues!! I can't believe how well this thing is working. I have played BF 3 and L4D2 for many hours so far and it's working great!! I've also played SC2 in OSX, but didn't notice much speed improvement over the 5870 I was previously using, even though Barefeats.com says there's actually a huge step up. I imagine the Windows version of SC2 runs much better.


Verdict

If you have the means, DO IT. This setup is stable and fast as sin. If you require boot screens, you can get supplemental power from an external PSU that's not too hard to rig up, or you can get a GTX120 which requires no extra power (older macs can use a GT7300 or Radeon 2600).
 
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I am also a GTX 670 user (hackintosh) and it is a very nice card.

pdm4w.jpg


But you should know that to get full OpenCL support, u need to patch. You can do this by downloading lib patches by netkas from here and put it into your /System/Library/Extensions/GeForceGLDriver.bundle/Contents/Bundle. (i recommend first copy out the kext to desktop, then doing this to the copy, then use kext drop to install the patched)
 
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I am also a GTX 670 user (hackintosh) and it is a very nice card.

Image

But you should know that to get full OpenCL support, u need to patch. You can do this by downloading patched lib from here and put it into your /System/Library/Extensions/GeForceGLDriver.bundle/Contents/Bundle. (i recommend first copy out the kext to desktop, then doing this to the copy, then use kext drop to install the patched)

You mean /System/Library/Extensions/GeForceGLDriver.bundle/Contents/MacOS/ , right?
 
Second card issues: I have a flashed 6870 as my slot 1 card so I can see boot screens. Windows apparently has a huge problem running AMD and Nvidia cards at the same time... basically I uninstalled my catalyst (AMD) drivers and everything works great. However, the 6870 is probably not very useful for gaming now without those drivers installed. Basically, when I initially installed the 670, the screen remained black in Windows until I uninstalled the AMD drivers. I've had no issues in OS X.

I thought this was fixed in Vista and higher. I ran NVidia and ATi in Windows 7 with no issues.
 
A couple of things: first off, I got the 2GB version, any more than 2GB and you have to hack the CUDA drivers to use that feature in Adobe / Apple's apps that use GPU acceleration help. You can download the CUDA drivers off of NVidia's website but with Mountain Lion, you need *NO* additional drivers to boot and start using the card.

To avoid any confusion, the CUDA requires NO FIXES WHATSOEVER. It is in fact OpenCl which has the 2.0 GB limit. This was Apple's choice.

MacVidCards discovered what the issue was, shared the info with Netkas who was actually able to FIND the tiny piece of code responsible and write a fix. It is very kind of Cindori to host the fix we worked out, would be nice if he mentioned where it came from.
 
Thanks for the review; Looking to upgrade from the Apple 4870 in my 4,1; Is it possible to run both the 4870 and the GTX670 in there without the use of a second external PSU?
 
Thanks for the review--it's always good to get someone's first-hand take.

The GTX 570 is plenty good for my gaming needs, I just would prefer the cooler, less power-intensive GTX 660 TI or 670. I've just read a lot of mixed reports of the 6xx in OS X...granted most of it stems from FCPX issues (which doesn't affect me).

Still, I'm leaning towards getting a cheap, used 570 on eBay or waiting for better 660 TI support. I have no clue what the likelihood of that latter is--I'm guessing it's dependent on a GTX 6xx appearing in an iMac or Mac Pro.
 
-xav8tor

Thanks; I went ahead and ordered the Gigabyte card from NewEgg along with a 6-pin to 8-pin power cable, however after sifting through the many pages concerning the Nvidia GTX5xxx & GTX6XX cards, it seems that using a power adapter is not recommended(I believe I saw MacVidCards had opined this). Any significant danger in using a 6-8 pin power adapter for one of the power cables?

Not really a gamer as I primarily use my Mac Pro for editing within Premiere CS6, Symphony 6 and motion graphics within AE and Cinema4D; I'm just starting to wonder whether I should return the GTX680 card and get a 570 from either NewEgg or a flashed one from MacVidCards, if OpenCL performance and especially Cuda are my main concerns(The 670 has more Cuda cores, however as I understand it that's not the be all end all in determining performance). Is there a significant drop off in Cuda/OpenCL performance in the GTX670 from the 570 if what MacVidCards has stated that the 6XX series were intentionally crippled by Nvidia so they could move more Quadro cards is true?
 
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-xav8tor

Thanks; I went ahead and ordered the Gigabyte card from NewEgg along with a 6-pin to 8-pin power cable, however after sifting through the many pages concerning the Nvidia GTX5xxx & GTX6XX cards, it seems that using a power adapter is not recommended(I believe I saw MacVidCards had opined this). Any significant danger in using a 6-8 pin power adapter for one of the power cables?

Not really a gamer as I primarily use my Mac Pro for editing within Premiere CS6, Symphony 6 and motion graphics within AE and Cinema4D; I'm just starting to wonder whether I should return the GTX680 card and get a 570 from either NewEgg or a flashed one from MacVidCards, if OpenCL performance and especially Cuda are my main concerns(The 670 has more Cuda cores, however as I understand it that's not the be all end all in determining performance). Is there a significant drop off in Cuda/OpenCL performance in the GTX670 from the 570 if what MacVidCards has stated that the 6XX series were intentionally crippled by Nvidia so they could move more Quadro cards is true?

I'll defer to the guys who know this stuff far better than me. I use CUDA some (no issues there) but primarily OpenGL. I certainly would be hesitant about the power adapter though. That's why I went with a dual six pin 670 SC 4 GB (EVGA). For sure, the OS X driver is immature at best. Even with PCI-E crippled on the Pro also in Win 7, the card really flies on the Windows side via Boot Camp.
 
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From what little I know, a 6-pin connector has dual 12V leads each carrying about 3 amps (6A total), while a 8-pin connector has triple 12V leads each carrying about 4 amps (12A total). So if you use an adapter, you could end up drawing about 6 amps through each lead instead of the 3 amps they may have been designed for. The problem is not the connectors or cables (those can handle the extra juice), but the amperage capacity of the traces in the main logic board of the Mac Pro and how much current they were spec'd for. We can only guess. Too much current and you'll burn a trace and the downside to a burnt trace on the main logic board is an expensive repair (new main board plus labor to swap it out), so the safe thing to do is just get a lower power card that only requires 6 pin connectors.

One other thing... if your card will run uncrippled with only 6-pin cables connected to it, you may be in luck (check with Gigabyte?). However, I believe most cards will run in a crippled mode when they are underpowered.
 
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Thanks guys for the input; As far as I'm concerned electricity is magic so I think I might just send it back and order a 570.
 
From what little I know, a 6-pin connector has dual 12V leads each carrying about 10amps, while a 8-pin connector has triple 12V leads each carrying about 10amps. So if you use an adapter, you're gonna run 15 amps through each lead instead of 10 amps. The problem is not the connectors or cables (those can handle the extra juice), but the amperage capacity of the traces in the main logic board of the Mac Pro and how much current they were spec'd for. We can only guess. Too much current and you'll burn a trace and the downside to a burnt trace on the main logic board is an expensive repair (new main board plus labor to swap it out), so the safe thing to do is just get a lower power card that only requires 6 pin connectors.

One other thing... if your card will run uncrippled with only 6-pin cables connected to it, you may be in luck (check with Gigabyte?). However, I believe most cards will run in a crippled mode when they are underpowered.

Uhh, AFAIK the extra +2 pins are just extra grounds.
 
So a extra sense, ground and the third +12V has become a requirement.

I was wrong, sorry. :) It's just that every PC I've built has always included the 3rd +12V on the 6pin connector.
 
So a extra sense, ground and the third +12V has become a requirement.

I was wrong, sorry. :) It's just that every PC I've built has always included the 3rd +12V on the 6pin connector.

Yeah, for some reason, PSU manufacturers include a third +12V lead on the 6-pin connector but a 6-pin card won't use it... while an 8-pin card could use it, without the added ground and, particular, the added sense, the 8-pin card with a 6-pin cable will likely run in crippled underpowered mode. If it doesn't run in low power mode or you use a 6-pin to 8-pin adapter to fool the sense, it will force the added current through the two ground leads which isn't desirable on a Mac Pro due to the traces on the main board as I mentioned above... you run the risk of burning out a trace with more current than it was designed to handle.
 
From what little I know, a 6-pin connector has dual 12V leads each carrying about 3 amps (6A total), while a 8-pin connector has triple 12V leads each carrying about 4 amps (12A total). So if you use an adapter, you could end up drawing about 6 amps through each lead instead of the 3 amps they may have been designed for.

From what I can tell, the 8 pin and 6 pin have the same number of 12volt leads, the 8 pin just has 2 extra ground. I'm sure the 8 pin run more power, but I think it's probable that the 2 extra pins do nothing but tell the card it's safe to draw that kind of power. All the same though, the 5870 (included with the mac pro) consumes more power than the 670GTX under load:


Power%20Consumption.png

http://www.tomshardware.com/reviews/radeon-hd-5870,2422-20.html

average%20load%20system%20power.png

http://www.tomshardware.com/reviews/geforce-gtx-670-review,3200-14.html
 
From what I can tell, the 8 pin and 6 pin have the same number of 12volt leads, the 8 pin just has 2 extra ground. I'm sure the 8 pin run more power, but I think it's probable that the 2 extra pins do nothing but tell the card it's safe to draw that kind of power.

The link above in post #17 explains the pin-outs better than I can. In short, A 6 pin has dual +12V, dual GND, and a single Sense lead. A 8-pin has triple +12V, triple GND, and two Sense leads. The Sense leads are used to tell the card what's connected and whether to draw the full power on an 8-pin connector or run in low power mode. The confusion arises because power supply manufacturers often include an extra +12V lead on a 6-pin connector that isn't required/used by the card.
 
I have used the 6 pin to 8 pin splitters before I had external PSUs.

They worked just fine...until they didn't.

With both a 4870x2 and a 9800GX2 I was able to make the overloaded power KILL the entire machine. As in a loud CLICK accompanied by sudden shut down.

The machine was fine but the scare was enough that I don't do that anymore.

For most of these cards, 99 out of 100 of you would likely have no trouble with a splitter. But since more than 100 people will read this, there will always be that 100th person who burns up their logic board traces.

The very first GTX580 I sold went to a rather silly gentleman who decided that not only would he use the 6 to 8 splitter, he would connect it and the other 6 pin to a single 6 pin outlet. He sent vociferous emails and left me several shreiking phone messages about the defective card I sent him.

He sent the 'defective" card back and it was just fine when connected with enough power.

Another guy recently had me mod a MSI Lightning GTX580. It has 2 @ 8 pin plugs on it. Against my advice, he has been running it with just 6 to 8 pin splitters.

Here is an email from him:

"Another issue I encountered this morning. Been doing some video editing and gaming on boot camp last night and then shut the Mac Pro off.

Tried turning it on this morning and all I got was a black screen. With some patience the screen turns grey after aprox 10 minutes and nothing really happens after that. Stripped the Mac to minimum configuration but no change. Works fantastic without the video card. Even works great with a PC 8800GTS I have here, tested both power cables and pci slots so it comes down to the video card. Tried both BIOS (thanks for modding both of em)

Any suggestion what's wrong with the card now? It worked so great last night ;("

He goes on to tell me that he had been overclocking and over-volting the card in Windows and it was just fine. Now, not so much. For some reason he refuses to accept that my prediction came true.

I have pointed out that he was supplying 150 watts to 2 inputs demanding the ability to draw 300 watts. He says I'm being hysterical.

I will close this by drawing another car analogy. Years ago I needed a new engine dropped into my Camaro IROC-Z. It had come with a 5.0 Litre engine but since I could drop a 5.7 litre into the same space and it would bolt right up, i did it. (like using 6 pin to 8 pin adapter)

At that point the car drove better than when I first bought it. All seemed better than new. If you had asked me in those first few weeks, I would have said it was a good swap. Then my clutch started slipping. I dropped a new clutch in and the acceleration was AMAZING. The car ran even better with the new clutch...right up until the transmission EXPLODED into shrapnel. Fortunately an old drunk woman pulled out in front of me when I had 13 miles on that $1,700 transmission installed. I would have kept blowing things up if she hadn't totaled the car.

The driveline of the car was engineered for the 5.0 Litre engine. Chevrolet didn't engineer extra capacity in. I got away with it for a little while, but at great cost. There is no reason to believe that Apple DESIGNED in the ability to handle 150 watts into each of those 6 pin connectors and their traces that lead back to the PSU. Yes, it may work for awhile, but it is not solid thinking to expect it to keep working into the future.

Either buy a card with Dual 6 pin plugs, or get an external PSU. GPU manufacturers don't put 8 pin plugs on cards just to look cool. They do it because the card draws more current than a 6 pin can reliably transmit over the long term.
 
I have pointed out that he was supplying 150 watts to 2 inputs demanding the ability to draw 300 watts. He says I'm being hysterical.

The only real question pertinent to this thread is: Does the GTX 670 draw too much power for the two on-board plugs to handle. Being as how it draws less power than even the Radeon 5870, and there are several GTX 670's with two 6-pin plugs, I'm not seeing it. [Edit: As someone else points out later in this thread, the reason this card has the extra 8 pin is so users can manually overclock it past the already-overclocked factory specs.]

I don't doubt many cards are capable of overloading the 6 pin plugs, I don't see how this can be one of them if it's drawing substantially less power than previous cards that have not. [edit: The 8 pin plug on this card is really only needed for manual overclocking.]

Electricity is not magic, more is more, less is less! Just because it's got a different plug doesn't mean adapting it is going to cause problems.

Edit3: I've looked at 4 different reviews, none of them say anything to suggest the GTX 670 uses more power than the Radeon 5870.

Edit: looking at the 580--the one you're pointing out issues with--it looks like the power draw is substantially more than the GTX670. The 5870, which functions presumably fine with two 6 pin plugs, draws more than the 670, but less than the 580

power-consumption.jpg

http://www.legitreviews.com/article/1925/13/

For comparison:

power_consumption.jpg

http://www.legitreviews.com/article/1080/13/

Edit2: it occurs to me that this particular card automatically over-clocks so it may be different from other 670's. As you can see from this review, it is still less than the 5870 (and less than the EVGA for that matter)

134301816907Bz8JXTOQ_10_1.png

http://www.hardocp.com/article/2012/07/25/gigabyte_geforce_gtx_670_oc_video_card_review/10
 
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The 8 pin is for overclocking purposes. If you don't overclock, it is highly doubtful that you need it. GTX670 that has 8 pin are using the GTX680 PCB. The chip itself is fine with 2x6pin and the extra components on the PCB is unlikely to make a huge difference. Most GTX670 that come on GTX680 PCB are overclocked but not enough to increase power usage significantly. It is when you dial up all the settings in the overclock utilities (EVGA PrecisionX for example) that you will see a difference.

btw the GTX580 a lot more power.
 
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