Are Mac Slot-In Drives regulated to lower speeds?

[Cox Orange]

I recently went through the specs of some Dual-Layer DVD Slot-in Drives, that are used in iMac G5, Powerbooks and Mac Minis.

I see that most Panasonic Mac optical drives end with -C and that they are slower in some speeds.

Example:
Panasonic/Matsushita UJ-85J-B and -C

DVD-RW 6x -B ----- 4x (UJ85J-C and UJ835-C)

+R (Double Layer) 4x -B ----- 2,4x -C


Could it be that Apple maybe "cut" the speed in favour of lower temperature?

 

[Altemose]

I wouldn't believe that Apple would cut the speeds intentionally. More than likely, they had that revision of part readily available at the time of the introduction of the line (iMac G5). Slot loading drives are always going to be behind tray loaders. There is just different adaptations which must be made for a slot loader than a tray loader.

 

[Cox Orange]

I am only talking about Slot-loaders.

Also, I do not think it is, what was available at the time, because the UJ85J- for example with the -B ending is faster than the same model with the -C ending (-C used in Apples).

Re: I recall the ibook drives going a bit loud and I suspect it might have to do something with noise, too, so that a faster drive would perhaps be even louder.

 

[Altemose]

I know you only meant slot loaders. Essentially Apple will use whatever part is available at the time that meets their criteria. Slot loaders will always be behind tray loaders so they generally went with whatever was most current at the time that they shipped the first of the line up. E.g. If Apple could ship 4x drives with the iMac G5 at the launch then they would continue to do so even though 8x drives may have became more common.

 

[Cox Orange]

I would think, that -C is the newer Revision than -B of the same model, but since -C is slower than -B, it must be not a Revision-marking, but something related to OEM or certain askings by manufacturers.

So I thought, since Apple always has the -C model from stock of each Panasonic/Matsushita drive (model UJ835, UJ845, UJ846, UJ85J), it must be a certain marking like "-C for Apple" and "-B for other OEMs" (Since the -B models are used in Sony, Siemens Laptops and Sun Servers).

If -B was just the earlier driver, why should Panasonic make it faster and make the next Version with the -C slower? This is why I thought it is not Revision number, but rather somethign other to devide them.

Maybe Apple told Panasonic "build us a special Version, with lower cost parts of the same, you have in your current catalogue" and Panasonic went like, ok then we take the UJxxx-B and just use another motor and append -C to make clear that it is the crappier Apple model.

So aside heat, cost might be the reason.

Still the numbering -B for the faster and -C for the slower does not make much sense.

 

[Altemose]

It doesn't make sense at all. I am thinking maybe it could do with noise too. Apple doesn't like loud machines, with the exception of the MDD PowerMac G4 .