Classic Mac Hardware (Troubleshooting, Upgrading, & Modifying) > Mac CPU Upgrades

MDD 866 Mods

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supernova777:

--- Quote from: Protools5LEGuy on September 23, 2014, 07:53:49 AM ---http://translate.google.com/translate?sl=auto&tl=en&js=n&prev=_t&hl=en&ie=UTF-8&u=http%3A%2F%2Fwww.macbidouille.com%2Farticles%2F89%2Fpage2&act=url

Anyone willing to take 133 bus MDD to a higher ground?

--- End quote ---

i have one.. but im afraid  :o :o :o

after i destroyed my quicksilver 867mhz i am not very brave with hardware mods :D

MacTron:
It is more difficult to pass from 166 to 172 Mhz. I've read the instructions once a year since 2003, and I'm still don't know for sure what is the quartz oscillator that must be changed (there isn't even a picture ) and where I can buy it...

Protools5LEGuy:

--- Quote from: chrisNova777 on September 23, 2014, 08:20:39 AM ---
i have one.. but im afraid  :o :o :o

after i destroyed my quicksilver 867mhz i am not very brave with hardware mods :D

--- End quote ---

To summarize all this post for ours MDD 866 there are 2 things to be done. The board is 133 bus and the cpu is 133bus...

On the motherboard back side



--- Quote ---for a bus to 167MHz: you must turn in the R676
--- End quote ---

And you have a 166 bus MDD board (heaven in OS9 I guess). This needs DDR RAM at 333 instead of 266 (?) so the original memory could not go 333.

You could buy a 166 MDD cpu or  mod the same 866 to be working on 166 bus.


--- Quote ---Bus 167 Mhz
R27 nothing, R22 nothing, Resistor R26
Bus 133 Mhz
R27 nothing,Resistor R22, Resistor R26
--- End quote ---
The thing that everybody talks about is that the 866 at 166 make fail the cache of the cpu,

--- Quote ---I have succesfully overclocked Dual G4 867mhz machine by changing the FSB from 133mhz to 166mhz, I removed the two resistors, R676 and R22. I have tested that the machine is stable in Xbench 1.3, Geekbench and in normal usage. G4 chips in my machine are RX933PC so they are rated for 933mhz and now working at 1080mhz.

But, I looked up the Samsung L3 cache chips on my processor card and as far as I know, they are rated for 250mhz (-HC25). L3 cache in MDD models with 1MB of it operate at 4:1 ratio, meaning that the cache in my machine is already operating out of spec, at 270mhz.
--- End quote ---


and also is recommended to take down the multiplier from 6.5 to 6.

From bits and multipliers...



--- Quote ---Step 3.   The table below outlines the PLL_EXT and PLL_CFG[0-3] settings for different bus and CPU speeds. For this example I am starting with a stock 1250MHz speed (7.5x multiplier) setting and upgrading to 1500MHz (9x multiplier) setting. The first number in the fields of the first column represents the PLL_EXT resistor and the following 4 numbers represent PLL_CFG[0], PLL_CFG[1], PLL_CFG[2] and PLL_CFG[3] resistors.

Example: 167MHz system bus and 1250MHz (7.5x multiplier) CPU speed is represented as:

PLL_EXT = 0 (resistor or bridged)

PLL_CFG[0] = 0 (resistor or bridged)

PLL_CFG[1] = 0 (resistor or bridged)

PLL_CFG[2] = 0 (resistor or bridged)

PLL_CFG[3] = 1 (no resistor or open)

Our target speed is 1500MHz (9x multiplier) - This is represented as:

PLL_EXT = 1 (no resistor or open)

PLL_CFG[0] = 0 (resistor or bridged)

PLL_CFG[1] = 1 (no resistor or open)

PLL_CFG[2] = 1 (no resistor or open)

PLL_CFG[3] = 1 (no resistor or open)

--- End quote ---

There in http://web.archive.org/web/20110722181011/http://bitsandpieces.info/Multipliers.htm is a table that says that our 866 on 166 would be 1083Mhz with
Search for the  "PLL Multiplier Config + Actual Speed on given bus"   table.


Try to buy the smallest soldering iron you can buy. For the JBC solders here in Europe you can find very thin tips for.
We have to be brave to live this era  ;)

Protools5LEGuy:

--- Quote from: MacTron on September 23, 2014, 09:08:31 AM ---It is more difficult to pass from 166 to 172 Mhz. I've read the instructions once a year since 2003, and I'm still don't know for sure what is the quartz oscillator that must be changed (there isn't even a picture ) and where I can buy it...

--- End quote ---

The instructions from bits and pieces, macbidoule, xlr8yourmac? What is the source of that info?

From bits... there are 3 zones to look out :

 a)PPL CFG (0-3)+ PPL EXT on processor side
 b)PPL CFG (0-3)+ PPL EXT on back side
 c)VID (0-4) on back side



From macbidoule there is also a zone to brake cpu to 133

Protools5LEGuy:

--- Quote from: MacTron on September 23, 2014, 09:08:31 AM ---It is more difficult to pass from 166 to 172 Mhz. I've read the instructions once a year since 2003, and I'm still don't know for sure what is the quartz oscillator that must be changed (there isn't even a picture ) and where I can buy it...

--- End quote ---
I guess the quartz oscillator is the same than the voltage generator (?), the chip on the VID (0-4). Maybe if you share your quartz oscillator instructions we can find out if it isn`t...

My references are here in this post ALL. Any more info, please, share here.

Is there any technician with skills to pull out the RAM of the CACHE of the cpu daughterboard and change it? Maybe is easier that what we thought to go 2 Mb cache.
In the
--- Quote from: Protools5LEGuy on August 13, 2014, 07:37:34 PM ---On Mac-Forums one guy make this...
http://www.mac-forums.com/forums/apple-desktops/164289-overclocking-dual-g4-mdd-867mhz-l3-cache-info.html

--- Quote ---I have succesfully overclocked Dual G4 867mhz machine by changing the FSB from 133mhz to 166mhz, I removed the two resistors, R676 and R22. I have tested that the machine is stable in Xbench 1.3, Geekbench and in normal usage. G4 chips in my machine are RX933PC so they are rated for 933mhz and now working at 1080mhz.

But, I looked up the Samsung L3 cache chips on my processor card and as far as I know, they are rated for 250mhz (-HC25). L3 cache in MDD models with 1MB of it operate at 4:1 ratio, meaning that the cache in my machine is already operating out of spec, at 270mhz.

Is there any software which I can use to verify the L3 cache speed? Xbench displays incorrect speed, ~4Ghz. I wonder if there is a way to modify L3 cache ratio to 5:1 so I could possibly overclock even further, to 1.25 Ghz? Probably I could just try and see if it can take it, but I would like hear if anyone in here has ever done overclockin for their Dual MDD 867mhz machines and was it how succesful?
--- End quote ---

--- End quote ---
 

there are references about the 1Mb cache of the 866 dual, limited to 250 MHz operating at 4:1 ratio working out of specs... What Samsung cache chips take the 1.42, 1.33 and 1.25 "golden duals". Is out there ANY reference of swaping the cache chips? 

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