" Motorola posted updated MPC7455 hardware specification (PDF file link), which is revised for XC7455A.
According to the document, the bus ratio of 2.5x - 4.5x are removed and the settings of 8.5x, 9.5x, 10.5x, 11.5x 12.5x, 13.5x 17x, 18x, 20x, 25x, 28x and 32x are added.

Furthermore, Vdd is lowered from 1.6V to 1.3V, and power consumption becomes lower too. This may be the reason that 1.25GHz processor module has a new core supply voltage circuit.

Because these specs are supported by XC7455 rev. 3.3 or later, current 7455/1.25GHz (rev. 3.2) may not support new bus ratio.
M . Isobe"

With a 32x max ratio (bus to CPU) that means even older Macs w/50MHz bus speed limits have a future CPU speed capability of up to 1600MHz (1.6GHz) - assuming a CPU becomes available that will run at that speed. That also means that 1GHz 7455 (rev 3.3) CPU upgrades for older macs are possible... but would the pricing make them worthwhile? (Considering the cost of upgrades vs the cost of a new/used/refurbished more modern mac with better graphics, faster bus/memory, onboard FW/USB, etc.)

The lower core voltage/wattage also is a plus for PowerBook G4 use.

" Mike,
Anyone trying to install the Encore/ST 800MHz or 1GHz in a Cube machine will have issues because we have not shipped the Sonnet Cube Installation Kit yet. The product will not install or work properly in a Cube without this kit. The kit will probably ship next month. -Joy
(Sonnet)

I'm writing the owner of the Cube/Sonnet 1GHz upgrade that reported the failure to ask how he installed it without a Cube heatsink adapter, etc.
Powerlogix's Cube dual 800 upgrade comes with some sort of heatsinks for the P.S. board also I'm told. I did not see any heatsinks for the P.S. board with the PL 1GHz review loaner and not sure they are required with that single CPU upgrade. (And again no other reports so far of any other single 1GHz Cube upgrade failures.)

Site sponsor OWC wrote regarding the dual G4/800 Cube upgrades:

" PowerLogix has asked us to suspend the sales of the Dual 800MHz Upgrades for the Cubes due to certain machines DC to DC converter not being able to handle the additional power requirement of a 2nd processor. In three cases, this DC to DC board has failed magnificently (smoked), but without causing damage to any other components in the machine. The good news is that this component is a plug in board, easily replaced. Within 2-4 weeks, shipments of the Dual Cube upgrades will resume and will have included a new beefier DC to DC board from PowerLogix. With this new board, the Dual 1GHz may even be offered for the Cube as the power requirements will likely be more than met for the faster model as well with the use of the new DC to DC board.

As an aside, we have shipped hundreds of the Cube 800MHz and 1GHz single G4 upgrades since August and not one has ever caused any issue with the Cube. It is only the Dual 800 Model that brought out the issue with the Apple DC to DC board. These PowerLogix boards are very well engineered and it is unfortunate that some of the stock DC to DC Cube boards aren't able to support the Dual version of the PL upgrade.

Only the Cubes have this DC to DC board due to their having an external power adapter. The PowerMac G4 models have no such issues with their internal power supply which had support for Apple's own Dual Processor system versions.
Best Regards,
Larry O'Connor
Other World Computing, Inc. "

Powerlogix's reply follows:

" PowerLogix has temporarily suspended shipments of the PowerForce Dual G4 Series 100 800MHz for PowerMac G4 Cube. This is due to a small number (3 to be exact) of failures of the Apple Cube DC/DC power supply card.

PowerLogix is currently putting the finishing touches on a more robust DC/DC replacement card for PowerMac Cubes, that will be able to easily support the added power demands of dual processors. This will also allow PowerLogix to offer faster dual processors for Cube systems, so Dual 1GHz will be a reality for Cube owners. The PowerLogix DC/DC board will also be available separately. Current Dual 800 owners will be provided the stronger DC/DC card at no charge when it becomes available.

The stronger DC/DC card is not required for single CPU models of the PowerForce G4 Series 100 although it would not be a bad insurance policy as the Cube ages. The card will also be much cheaper than Apple's replacement part cost.

Customers who currently own or acquire a single 800MHz or 1GHz PowerForce G4 will be able to upgrade to dual models through the Trade-up program. This means Cube owners can upgrade their systems now for a tremendous speed boost, and upgrade again later for even more speed without a price penalty.

Even though the PowerMac Cube was not a big seller for Apple, it is a big part of the Powerlogix product offering. A stronger, more robust DC/DC card combined with a PowerForce G4 CPU upgrade will enable owners to enjoy both high performance and long life from their Cube
Robert Jagitsch
Powerlogix "

" I bought a 17" iMac in this month and it also has the non-Pioneer DVD-R/CDRW drive. So far I have only been able to burn a DVD with a Mac DVD disk. (I assume he means the Apple boxed DVD-R discs but wrote to ask.-Mike) Some Memorex disk that I got would not even stay in the drive, the drive would do some grinding and then spit it out. Those same disk worked on my G4 Tower. I also tested the Memorex disk in a demo 17" iMac at our Campus Computer store and it had the same problem.
So far I haven't had anytime to get hold of Tech Support and ask them for a solution to the problem.
Robert C.
Macintosh Systems Engineer
Office of Educational Technology
University of Illinois
(he later wrote

Yes I mean the Apple branded disk. I talked to Apple today and the tech support person says that yes they are different drives and that Apple doesn't guarantee that any disk other then their branded disk will work with the SuperDrive. I told them that their FAQ states that any DVD-R general disk will work and that they should state on the 17" iMac page that only the Apple Disk are guaranteed. Also I asked if the Apple branded disk were Verbatim and he would not verify that as true. "

If any other iMac G4 owners with the LG (non-Pioneer) DVD writer has seen problems with other DVD-R/RW media, let me know.

• Other World Computing G4/450 in B&W G3 (rated 10)
• Powerlogix G4/800 in G4 Cube (rated 5)
  (noted freeze when L3 cache enabled)
• Sonnet G4 1GHz in G4 Cube
  (noted apparent PS Board failure)
• Sonnet G4/800 in 7600/132 (rated 10)
• Sonnet G4/800 in 8600/300 (rated 9)

(Warning - Overclocking may not be reliable and could lead to hardware failure or corrupted data.) You can find the full reports by searching the database selecting the indicated Mac model and upgrade card brand/type. If you've upgraded the CPU on your Mac, please post an entry in the database. Search the database for entries from most every upgradable Mac model *before* you buy. (Searchable by mac model/upgrade brand). For detailed reviews with performance tests and install tips, see the CPU Upgrades page.)

Combo DVD+CDR Reports:
• IDE LG 4120B (12x8x32x + 8x DVD ROM) in G4/AGP (OS X)
  (didn't comment on itunes or discburner support)
• IDE Plextor PX-320A (20x10x40 +12x DVD ROM) in G4/AGP (OS X)
  (no itunes or discburner support)
  
  IDE CDRW Drive Reports:
• CenDyne CW4001 (40x12X48) in Dual G4 DDR (OS X)
  (listed under "other" brands - no itunes/db support)
• Lite-On LTR-48125W (48x12x48x) in Dual G4 (OS X)
  (drive sleep issue if disc left in drive)
  (FYI - Illustrated CD drive install guide here covers G4 towers up to the Digital Audio Model, Beige G3 MT, B&W G3 and 8600/9600 Macs.)
  
  Firewire CDRW Drive Reports:
• Lite On LTR-40125S 40x12x48 in FW case used w/7500 (OS 9.1)
  
  SCSI CDRW Drive Reports:
• Yamaha 6416SX (6x4x16x) used w/8500 (OS X)
  
  IDE Hard Drive Reports:
• IBM Travelstar 40GNX 20GB in PowerBook G3 wallstreet2 (OS X)
  (some problems noted - seeillustrated HD install guide here for PB G3 wallstreets)
  
  Removable Media Drive Reports:
• Firewire PCMCIA slot Fujitsu MCJ3230AP (MO) 2.3GB used w/Powerbook G3 wallstreet2 (OS 8.6)

You can find full owner reports (latest shown first) by searching the database by drive/brand/interface/mac models (the latest reports are shown first in searches). For guides to installing CD/CDRW/DVD drives or Hard drives in many mac models, see the IDE Articles page. The Firewire articles page also has guides on case kits, installing drives, etc.
If you've added a IDE, SCSI, Firewire or USB hard drive, CDRW, tape drive, etc. make sure you add a report to the database. [If you post an updated entry - make sure you use the same name, etc. as you did before so I can find your past entry. Thanks.]
(Entries today will be added the following newsday. Incomplete entries are deleted. Do not post questions in the database, it's for drive reports not questions on what drive to buy - for that try searching the database for reports from owners of your mac model on the drive type/brand/interface, etc. you're interested in.)

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