1.25 Dual CPU interchangeable?

[kenji]

Hi, are the Dual G4 1.25 GHz CPU from MDD FW400 compatible with the FW800 Model motherboards? I think those from FW400 has 2 MB L3 cache while those from 1.25 GHz FW800 has 1 MB each. Is the L3 cache a deciding factor? Also which motherboard is more reliable, ( I mean less prone to failure) those from FW400 or FW800? Thanks

[aquamac]

Kenji,

Yes the processors are interchangeable. The later Dual 1.25's (from FW400) do indeed have 2 megs cache per processor. As for which logic board is better, I would say the FW800 as it has built in Airport Extreme & Bluetooth. However these are generally the only differences you will note. My FW800 has been steadfast though many mods, but then again so has my FW400!

[kenji]

Thanks aquamac

[reddrag0n]

On reply to this, since you know more about the MDD's more than i do, which one is the faster out of the boards? I know there were several revisions out there, but knowing which one is faster would be a good piece to know.

EDIT: This is what i mean...
167MHz 661-2782
133MHz 661-2781
167MHz 661-2839
167MHz 661-2812
167MHz 661-1771
133MHz 661-1774
133MHz 661-2631

[aquamac]

Hi JJ,

The 167 bus boards are the fastest, 2782 & 2839 support onboard bluetooth & Airport extreme, but any board that is 133 bus can be changed to a 167 bus by removing just 1 resistor from the back of the board. Other than the bus there is no difference in speed that I am aware of. The 2812 is the last MDD logic if you were going for a non AE/BT board & theoretically should have more bugs squashed from it than earlier boards of this type. My recomendation though would be 661-2839.

[B B]

Hi aquamac,
I would add something you know but did not mention : the 133 Mhz Mobo works with 266 Mhz Ram PC2100 and the 167 Mhz Mobo with 333 Mhz Ram Memory PC2600.

Nice compil reddragOn

[reddrag0n]

Thank you bb, took me some time to compile all the revisions into one well shown pic.
Of what i have heard about the MDD machines, is it true that you can use PC-3200 DDR ram in them too? What about 1GB sticks? Can they be used or just the 512MB sticks? If the 1GB's can be used, can the machine be boosted to 3 or 4GB of ram?

[aquamac]

Hi Guys,

Thanks for the reminder bb. JJ, as bb says, nice work! 1 Gig sticks work fine in MDD's, as does DDR 400 (PC3200 - but it is seen as PC 2600 in FW400 due to a bug in sys profiler/logic board) as it is backward compatible. FW800's see DDR400 or DDR 333 as PC 2700. In fact I have tested both Kingston & Corsair value ram 1 gig DDR 400 in both my MDD's and they work fine. I have 2 x 1 gig sticks in one of them & have used for 8 months with no problems. If you stick in 4 x 1 gig sticks only 2 gigs will be recognised as that is the max the board can see - you guessed it, I tried it! Interestingly, sees them all as 512's.

[B B]

reddrag0n said:

Thank you bb, took me some time to compile all the revisions into one well shown pic.
Of what i have heard about the MDD machines, is it true that you can use PC-3200 DDR ram in them too? What about 1GB sticks? Can they be used or just the 512MB sticks? If the 1GB's can be used, can the machine be boosted to 3 or 4GB of ram?

I do realize the time you needed to spend to get this in one pic.
Yes indeed you can use PC 3200 DDR Ram . And also 1Gig sticks . But the max Ram accepted by the system will stay 2 Gb. I put two Corsair 1 Gig sticks and I added sticks cooler later and as aquamac says, it's working fine.

[kenji]

admin said:

Hi Guys,

I have 2 x 1 gig sticks in one of them & have used for 8 months with no problems. If you stick in 4 x 1 gig sticks only 2 gigs will be recognised as that is the max the board can see - you guessed it, I tried it! Interestingly, sees them all as 512's.

Hi everybody,

I'm a bit confused: Given that the MDD can only recognize 2 GB of total memory, does it mean that:

1. If you place 1 GB stick in one memory slot, it will be recognize as 1 GB?
2. If you place 2 x 1 GB sticks, both will still be recognize as 1 GB fro a total of 2 GB?
3. If you place more than two 1 GB sticks, all will be recognize as 512 MB only since the maximum the MDD can recognize is 2 GB?

I always thought that the MDD can only accept 512 MB sticks in each memory slots.

[reddrag0n]

According to aquamac and what i have seen of his mods, this is how it works...

slot 1, 2, 3 & 4 can handle 512 meg and 1 gig sticks. (2) 1 gigs total, or (4) 512 meg sticks.
A combination of the two will not work (maybe it does) one 1 gig and two 512's to make 2 gig total. Of what i understand, the motherboard looks at 2 gig of ram MAX.

If i am wrong about this, please feel free to correct me on this for this is something i do not know the full details on.

[aquamac]

Yes you are right Kenji & JJ. I have tried to do some research on this to find out if 32 bit OS's are the problem or whether the system is hardware bound at 2 gigs, but as yet nothing conclusive. I have a feeling that it may be a processor/northbridge problem, if anyone has any other ideas, please correct me.

[reddrag0n]

ok, so here is an idea, on your machine running two 1 gig's, throw in a 128, 256 or a 512 in also and see what the "About This Mac" and "System Profiler" say. What better way to find out if it will work than to try it. If it works, it should boot, or give you error code beeps.

[kenji]

wow, we're getting more on technical details here ;D So the way I understand it, it goes like this:
1. The MDD can accept only a maximum of two sticks of 1 GB memory to be able to see the whole 2 GB.
2. The memory slots of (or whatever term is applicable) MDD is not limited to 512 MB memory not like the slots of B&W G3 which were limited to 256 MB and earlier G4 which were limited to 512 MB.
3. Although we can place 2 sticks of 1 GB memory on MDD to make it 1 GB, mixing it with 512 or 256 MB on other slots will make the 512 and 256 unuseable since the maximum of 2 GB is already attained by the two sticks of 1 GB.

Did I get it right?

[aquamac]

I have tried 3 x 1 gig sticks and 4 x 1 gig sticks but only see 2 gigs. I will try say 2 x 1 gig sticks tonight with a mixture of 256 & 512's to se if there is any benefits. Will post back later.