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PCI slots on G5


Active Member
A friend of mine talked to a higher tier level tech support guy from Apple and the guy told him that PCI slots 2 and 3 get 800 MB per second combined and slot 4 is 1064 MB per second which would lead him to believe that 2 & 3 share a bus and therefore 4 should be used for your most critical audio PCI card. Can anyone either confirm or debunk this? If so, should my Layla be on Slot 4 and my UAD-1 in 2 or 3 or vice-versa?


Active Member
OK, I got confirmation from several sources that this info was correct. Slots 2 and 3 share a bus while 4 is alone and is faster. So your most critical audio card, in my case the Layla 24, should be in 4 and others in 2 or 3. But since the UAD-1 is a litlle on the finicky side, would it be better to put the it in 4 and the Layla in 2 or 3? I suspect not but if someone from UAD or a more knowledgable user here could make a definitive statement about this is would be helpful for us G5 users.


Universal Audio
UA Official
Hey Buddy,
I know I talked to you on the phone today, but I'm just posting this for redundancy and for the other readers: We have found through testing that you will get the best performance out of the G5s with separate buses when you put your PCI sound card in slot 4 (the separate bus) and putting the UAD-1(s) in slots 2 or 3. If you have a UAD-1 and PoCo this would be the same they would go on either 2 or 3. For users of FireWire interfaces you may have to experiment with which slot works best and for G4s or G5s without dual PCI buses, this is obviously a moot point (there is only one bus).
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