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Most Powerful GPU for Quad G5 ?

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Hi all

Tomorrow, I'll be picking up my first G5, a PowerMac G5 Quad (top of the line, late 2005). It's in great shape, near mint and best of all, I only paid 10 euros for it!


The seller formatted the hard drive, so I need to reinstall OSX. Currently burning a DVD-RW as I'm typing. Don't know yet how much RAM it has, but it does have the optional long bluetooth antenna thing on the left hand side. Yeah! Bluetooth Mighty Mouse here I come! But I still need to get the display, mouse & keyboard separately... Damn! Those HD Cinema displays are so EXPENSIVE! I'll have to live without one for a while until I find a really cheap one.


Anyway. I'm already looking at a replacement GPU. The unit has the standard GeForce 6600 with 256Mb of VRAM. The latest, most powerful MAC-compatible GPU is the Quadro FX4500. But I read here that a flashed 7800 GTX performs much better than the quadro. How hard can it be to flash a PC card? Should I buy a Quadro or a 78000GTX? Do I need a PC with a PCI-e port to flash to ROM?


It's my first desktop computer, and usually, I'm not really into modding, hence the stupid questions.



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What are you wanting to do with it?


If you're planning on heavy gaming or just want raw performance you'll want the 7800GT/GTX. Keep in mind that a "flashed" card may be for a Mac Pro, not a G5, so make sure it's promising G5 compatibility. The Quadro is more of a "workstation" graphics card, so while it has 512MB VRAM it's slower overall.


There was also a Radeon X1900 upgrade, but you have to be careful getting one of those, because the Mac Pro had that as its top-end card. The G5 version is a single slot card without vent slats.


Now, all that said, the 6600 is not a bad card by any means, and depending on what you are doing, you might just want to stick with it while you get the other stuff you want.

Edited by TheWhiteFalcon
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The fastest option would be a GeForce 7800GTX 512MB.

You could also go for 7800GTX 256MB or the 7800GT.

The 256MB 7800GT was BTO back then. Finding one of those BTO cards will be next to impossible so you probably want to go the route of getting a standard PCIe 7800GT and go hunting for a ROM to flash.

You will have to solder on a larger flash chip as all 7800s I have seen so far come with a 64KB chip which is too small for the Open Firmware ROM to fit.


Flashing has to be done in a PC or in an external programmer as you are going to have to solder on a new flash chip anyways.

Edited by Bolle
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There are four common GPU options for the late '05(PCIe) G5s


1. The 6600 variants, which were the standard ones


2. 7800GT(mid-range BTO)


3. Quadro FX4500(high end BTO)


4. X1900GT(retail)


The Quadro is a big "sexy" card that everyone wants. The official G5 version can usually be had in the $50-75 range. They are also easy to flash if you get the right base card, although I've not personally done it.


Per OpenMark benchmarks, my X1900 significantly outperforms all my other PCIe G5 GPUs, including the FX4500(although it's not as fast as the X800 or X850 for the AGP G5s). This card also has the advantage of being single height, and is the only single height PCIe G5 card with two dual link DVI ports. It's the card I'd suggest if you can find one. 


Otherwise, I'd go with a 7800GT-these cards are readily available and are a big step up from the 6600.

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Thanks guys for the replies! I'd like to play a few games on this machine, so a better GPU is in order!


I'm having trouble finding ANY 512mb 7800 GTXs... All I can find is the 256meg one. It must be some rare beast or something.

So let's narrow it down to the FX4500 and the X1900GT. Because the chances of finding a cheap 512meg 7800 are slim. The X1900GT is a 256meg card, right? Doesn't that mean that it's "not as good" as the 512meg Quadro ? I tend to think the bigger the better, but maybe I'm wrong?


I didn't know the cord was so important. I never poked my head inside a G5 so I didn't know about that. Good to know. Thanks again!


Falcon: so the ROM from the Mac Pro card won't work on a G5? Didn't know that either...

Edited by BadGoldEagle
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There are a lot of Quadros & X1900GTs available for sale. Some of them are for PC. Is there a quick way to tell which one's which? 

What happens if you put a PC card in a G5?


Edit: the GeForce 7800 GT and the X1900GTs seem to be relatively the same performance wise.  

Edited by BadGoldEagle
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I'll try to photograph mine tomorrow if I remember to. It's in the G5 Quad I use(occasionally) at work.


Generally, if you put a PC card in a PPC Mac the computer MIGHT not boot or(more likely) the computer will just ignore the card.


Interestingly enough, since OS X 10.7 it's been possible to use a lot of off-the-shelf PC GPUs in Mac Pros. You just don't get boot screens.

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Also note that the 2-slot coolers (like on the Quadro or a flashed 7800GTX) should be quieter than the single-slot 7800GT--much bigger fan/heatsink. And you're still left with 2 slots.

I have a 2.0 DC G5 and got a good deal on an OEM Quadro from eBay.

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