View Full Version : Workaround to Crippled PCI in G5 Dual 1.8?

02-27-2007, 09:54 PM
Might there be a workaround to the notoriously crippled PCI in the G5 Dual 1.8? About a year ago, TZ said:


The G5 1.8's are truly "crippled" when it comes to PCI bandwidth. They ain't got a lot. Good at reading data, poor at writing… an Apple firmware update put what can only be called a 'govenor' limiting writes to 75MB/sec (does NOT affect the two internal SATA ports).


So the connectors in the bays intended for internal drives are crippled, but there are other SATA connectors in the case? Does this mean I could ignore the bad connectors and add a few cables to boot and run data off the good SATA ports at normal PCI speeds?

Alternatively, is there a way to remove the bad firmware updat?

The quotation comes from a great thread that grew in the wrong forum, so I'm moving it here.


02-27-2007, 11:28 PM
The PCI bus is crippled. Doesn't have anything to do with internal drives on the motherboard SATA bus. Well, not as directly since a single SATA drive is not any faster than the bandwidth limitation..

The problem is not firmware. The problem is the combination of hardware installed on that motherboard that gives horrible speeds through the PCI-PCI bridge. Unfortunately, that component passes everything: USB, Firewire, internal ATA running the optical drive, internal SATA, the AGP graphics and, the PCI bus itself.

There is quite literally nothing I have ever heard that will make this milk toast motherboard give decent performance. Apple should have been ashamed enough to recall all of them, IMHO. The PCI bus is significantly slower than ANY AGP G4 preceding it. That is over 6 years of G4s that outperform it.

My sympathies to you for the situation that puts you and all the other owners in. The machine is not capable of all that much, and that is the fact.