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GeForce GTX 280 on a mac pro??

ildondeigiocchi said:
The Mac Pro dedicates 300Watts for graphics cards. The GTX 280 requires at max 236 WAtts, Nvidia says so on their web site. The 500 watt requirement is for the whole system and the Mac Pro has a 1.2 KW power supply which more than does the job. However, if you also want to keep a 8800 GT in it which requires 107 watts at max load you will have to connect it to the molex connectors in the 2nd superive which will work fine and will Not do anything to your system. Worth a try.
Click to expand...

300 Watt is what the Mac Pro can supply through the four PCI-Express slots.

One PCI-Express slot can electrically wire 75 Watt and the Mac Pro has four.

What this essentially means is that the Mac Pro can supply 4 x 75 Watt = 300 Watt of power through the PCI-Express slots but only 75 Watt per slot.

Then comes the power cables from the motherboard and direct power from the power supply.
 
So, recap.

I have my original card plugged in, only I moved it up one PCI slot. I plugged in the GTX 280 into the lowest slot. I connected it to the 6 pin power supply on the motherboard, AND I am also running a cable down from the molex supply from the additional optical drive to the 8 pin power supply in the video card.

I am getting a red light on the video card, which the vendor says means "not enough power".

Frustration :(
 
europeo said:
So, recap.

I have my original card plugged in, only I moved it up one PCI slot. I plugged in the GTX 280 into the lowest slot. I connected it to the 6 pin power supply on the motherboard, AND I am also running a cable down from the molex supply from the additional optical drive to the 8 pin power supply in the video card.

I am getting a red light on the video card, which the vendor says means "not enough power".

Frustration :(
Click to expand...
I'm not sure this would help, nor why it should be any different, but have you tried switching the card location? It may be a peculiarity with Apple.
Put the original (2600XT) in Slot 1, and the 280GX in Slot 2. I can't remember if the 6pin PCIe power connectors on the logic board are labeled for a specific slot. :eek:
Can anyone answer this BTW?

Other than that, it may be a bad 280GX. :( A simple, last attempt anyway. Sad to see this has become such a PITA, especially since others have already gotten a 280GX working. :eek:

Good Luck. :)
 
Pressure said:
300 Watt is what the Mac Pro can supply through the four PCI-Express slots.

One PCI-Express slot can electrically wire 75 Watt and the Mac Pro has four.

What this essentially means is that the Mac Pro can supply 4 x 75 Watt = 300 Watt of power through the PCI-Express slots but only 75 Watt per slot.

Then comes the power cables from the motherboard and direct power from the power supply.
Click to expand...


Accordin to what you've just said almost no card would work in the Mac Pro. Since 8800GT requires 107 Watts and according to you there is only 75 watts in each slot, then the card shouldn't work but in reality it does so your theory is wrong. :)
 
ildondeigiocchi said:
Accordin to what you've just said almost no card would work in the Mac Pro. Since 8800GT requires 107 Watts and according to you there is only 75 watts in each slot, then the card shouldn't work but in reality it does so your theory is wrong. :)
Click to expand...

All cards that require more power comes with either a 6-pin or 8-pin or both connectors so that you can run power directly from the power supply to the graphic card.

PCI-Express slots can max wire 75 Watt and adding another 6-pin connector gives you around 75 Watt more power (depending on the power supply), meaning you are now looking at 150 Watt of supplied power. More cables, more power ;)
 
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