Getting a new MDD motherboard

[MatthewLTL]

A kind user on MR has mailed me a MDD FW800 167MHz motherboard.

Thing is my Processor is only the 133MHz 1GHz model, One user on here suggested it would indeed overclock to 1.25GHz. Is this true? Could i USE my current CPU or do i have to set the new board to the side when i get it and order me a 167MHz CPU?

 

[MatthewLTL]

Anyone? Intell? Altemose?

 

[Intell]

You could use it, but it won't run at its proper speed.

 

[MatthewLTL]

You could use it, but it won't run at its proper speed.

what speed will it run at?

 

[Intell]

Less than what it is rated for.

 

[MatthewLTL]

Less than what it is rated for.

Wait, What? The CPU is a 133MHz FSB. If used in a 167MHz motherboard wouldn't the CPU run faster?

 

[Intell]

No, it would clock down.

 

[MatthewLTL]

No, it would clock down.

Why?

 

[Intell]

Because that's how the the multiplers work.

 

[MatthewLTL]

Because that's how the the multiplers work.

I dunno what that means but it seems backwards

 

[bunnspecial]

Because that's how the the multiplers work.

Intell,

I trust you implicitly on this stuff and assume that you've probably done exactly this at some point, but I'm having a bit of trouble following this also.

On a 133mhz FSB board, a 1ghz CPU is running at 7.5x. Assuming that the multiplier is hard-coded to the processor card(which I realize may not be a valid assumption) if that same CPU were transplanted to a 167mhz FSB board, it should run at 1.25ghz.

Are you saying that's not the case?

 

[Intell]

They downclock. It's odd I know, but that's what they do.

 

[bunnspecial]

They downclock. It's odd I know, but that's what they do.

Thanks-as I said, I always figure if you say something is so, it's probably because you've actually tried it

 

[MatthewLTL]

They downclock. It's odd I know, but that's what they do.

Downclocks to what?

If the 133MHz processor downclock on a 167MHz FSB board than what do the 167MHz FSB CPUs clock to on a 133MHz FSB board?

 

[Intell]

I don't remember what they downclock two. They downclock to the highest speed ratio attainable on the bus without going over their set clock speed.

 

[MatthewLTL]

I don't remember what they downclock two. They downclock to the highest speed ratio attainable on the bus without going over their set clock speed.

I plan to get a faster CPU anyway (hence why I was after and am recieving a 167MHz FSB board). As long as you can assure me the MDD will physically boot with a 133MHz CPU in there that's all that matters at this point.

 

[bunnspecial]

I don't remember what they downclock two. They downclock to the highest speed ratio attainable on the bus without going over their set clock speed.

If that's the case, 6x would give 1002 mhz and 5.5x would give 918mhz

 

[MatthewLTL]

If that's the case, 6x would give 1002 mhz and 5.5x would give 918mhz

Long as I can still run Leopard

 

[bunnspecial]

Long as I can still run Leopard

Any AGP G4 can run Leopard with zero issues

 

[MatthewLTL]

Any AGP G4 can run Leopard with zero issues

thats assuming it has the 867MHz CPU requirement otherwise it's extra work. I take it the PCI G4s can't?

 

[Intell]

thats assuming it has the 867MHz CPU requirement otherwise it's extra work. I take it the PCI G4s can't?

It is minimal work to bypass the 867Mhz check. PCI based Macs with a G4 can, but more work is involved.

 

[bunnspecial]

LeopardAssist makes bypasssing the 867mhz check trivially easy-you literally just run the program and restart the computer into the Leopard installer. It's also not a lot more work to do it from Open Firmware.


As Intell says, PCI based G4s do require more work. I've been tinkering with one on and off for a few months(admittedly a G3 upgraded to G4, but in actuality nearly identical to the PCI G4), and still haven't been able to get there.

 

[MatthewLTL]

LeopardAssist makes bypasssing the 867mhz check trivially easy-you literally just run the program and restart the computer into the Leopard installer. It's also not a lot more work to do it from Open Firmware.


As Intell says, PCI based G4s do require more work. I've been tinkering with one on and off for a few months(admittedly a G3 upgraded to G4, but in actuality nearly identical to the PCI G4), and still haven't been able to get there.

well the fact i see no difference in preformance for Leopard on my eMac with 512MB RAM and my MDD wiith 1GB i assume I'll see little difference in a underclocked CPU (Does this mean the CPU will run at cooler temps?)

 

[LightBulbFun]

regarding the down clock feature if they down clock not to go over there rated speed then How dose Over clocking 1.42Ghz MDD modules work then? since all there doing is changing the multiplier in relation to the bus speed to attain a higher speed (which you say would actually down clock since the CPUs are not rated for higher?? unless theres something Im missing?)