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How to change the FSB on a MDD
- Thread starter Unknown_K
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As far as I know, there is no known way to increase the bus speed. I've seen instructions on how to increase the multiplier (involves desoldering and resoldering micro-resistors on the CPU card,) but not the bus speed.
Plenty of info on the mod
http://bitsandpieces.info/Multipliers.htm
http://www.xlr8yourmac.com/systems/g4_mirrored_drive_doors/G4_MDD_CPU_Module.html
... I also recall a guide on the Macbidoulle/Hardmac site, but can't find it (it was most relevant to the 133 to 166 FSB overclock)
I recently aquired a later model FW800 single 1Ghz machine, 133FSB, and could not get it up to 166FSB - it just reported the former 133 FSB. I suspect the later model boards are fairly different. It also had issue with a PC flashed Geforce 6800 Ultra, which worked fine in other Macs (pins covered etc).
If the 166FSB alteration doesn't work, there is always adjusting the multiplier on the CPU card itself; for a 1.25 DP you should get 1.42 out of it.
JB
http://bitsandpieces.info/Multipliers.htm
http://www.xlr8yourmac.com/systems/g4_mirrored_drive_doors/G4_MDD_CPU_Module.html
... I also recall a guide on the Macbidoulle/Hardmac site, but can't find it (it was most relevant to the 133 to 166 FSB overclock)
I recently aquired a later model FW800 single 1Ghz machine, 133FSB, and could not get it up to 166FSB - it just reported the former 133 FSB. I suspect the later model boards are fairly different. It also had issue with a PC flashed Geforce 6800 Ultra, which worked fine in other Macs (pins covered etc).
If the 166FSB alteration doesn't work, there is always adjusting the multiplier on the CPU card itself; for a 1.25 DP you should get 1.42 out of it.
JB
Did that once. It's not hard
There's resistor settings on both the motherboard and the processor card for determining bus speed. If either one is set to 133mhz then the bus will run at 133mhz. If you're changing the processor that would solve that problem.
To change the resistor setting on the motherboard you need to remove R676. It's located on the bottom of the motherboard right under the rear left corner of the processor socket.
In case you want to play with your currant processor. On your dual 867 card you need to remove resistor R22 to change it's bus setting from 133 to 167. It's on the top of the card to the rear of the left hand processor. If you don't do anything else your 867 will be trying to run at 1083mhz. It may or may not do that. Mine had 933mhz processors and handled it but I may just have been lucky. There's lots of info on the web on overclocking MDDs. I should point out that there's a separate set of resistors for the speed setting of each processor.
There's resistor settings on both the motherboard and the processor card for determining bus speed. If either one is set to 133mhz then the bus will run at 133mhz. If you're changing the processor that would solve that problem.
To change the resistor setting on the motherboard you need to remove R676. It's located on the bottom of the motherboard right under the rear left corner of the processor socket.
In case you want to play with your currant processor. On your dual 867 card you need to remove resistor R22 to change it's bus setting from 133 to 167. It's on the top of the card to the rear of the left hand processor. If you don't do anything else your 867 will be trying to run at 1083mhz. It may or may not do that. Mine had 933mhz processors and handled it but I may just have been lucky. There's lots of info on the web on overclocking MDDs. I should point out that there's a separate set of resistors for the speed setting of each processor.
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