Geekbench Score is about 680 Points. Should i also try the e5450
I will try to describe what i have done. Most parts are described much better (written by native speakers
) in other communities.
If your fine motor skills are bad, this mod is nothing for you
Overclocking is an iterative process, you change settings, system will crash, you change them again, system will crash and so on....
If i tried Overclocking on the Mac Pro, i would be forced to disasamble the CPU's on every try, this would have drive me nuts. There is no software (i mean bios) overclocking functionality. So i choose a Socket 775 Platform to evaluate the CPU's capabilities.
On most socket 775 Boards, overclocking is very easy. We need an FSB of 400MHz so only "good" P45 and P35 Boards will work. Just watch Youtube or search for 775 Overclocking on google.
I talked about 775 but the MAC CPU's are all 771. Some smart guys found out, that with slight socket modifications the 771 CPU's work in some 775 Boards (google for 771 xeon mod).
Two pins must be swapped with a litte bit of tape (xeon mod sticker) and you must cut out some plastic notches.
So if you got a running 775 Platform, you can start with overclocking it. First find out the default Vcore (eg. with cpuZ).
Then you can set the FSB to 400MHz and increase the vcore until the 775 runs stable. For me, there was a big jump between "stable for 1 our" and "stable over the night". My first CPU seems to be stable at 1,25V but needed another 50mV to be "rock stable". Don't "overcool" the CPU in the PC board, the Mac will run them until the termal limit is reached.
Because the Mac Pro does not have overclocking capabilitys, whe must "hardcode" these Settings.
FSB selection on Socket 775 and 771 was very easy. Only 3 Pins on the CPU are responsible for the FSB. These Pins are only red on start and these pins do have static voltage on them.
The voltage selection on 775 and 771 is simmilar, but there are 6 pins, for a voltage range from 0,85 to 1,6V (!!!).
If you hide a pad of the cpu (with some tape) the voltage in the socket pin goes to High. If you connect a pad with another ground pad, you got a LOW.
Let's begin with the FSB:
You are coming from FSB 333MHz and whant to change it to 400MHz so you must change BSEL1 to HIGH according to the table, because only on BSEL1 is a difference.
Here is the example of the 775 socket FSB Sel Mod from 333 to 400. On 771 the notch on the right side is nonexistent, but you must tape the same pins. The Triangle for orientation is hidden on this picture, it's on the left handed side.
With a higher frequency the CPU needs more current, so you need to higher the voltage.
Every CPU is an unique, so there will be a unique Vcore you must chose for your CPU.
My CPU's came with a standard Voltage of 1,215 and 1,2V and i added around 100mV.
These 100mV was not a guess,
According to this table, i had to change VID6, VID5 and VID4 on both CPU's (1,215->1,315 and 1,200->1,300)
In the appendix you will find a nice exel tool which will do the math for you, its from the hardwareluxx thread.
It looks like this:
Again: The two notches are for socket 775, your orientation is always the triangle.
Taping the Pins is "easy", connecting two pins is more difficult. I used my soldering iron to connect these two pins and used a nail file to make the solder points flat. I had also tried conductive ink, but it contaned only carbon and the impedance of the conection was far to high. Please search what kind of ink does work.
If you did all these modifications, tripple check the positions and put the CPU back in your 775 System (and do a bios Reset). If you messed it up, your CPU will run very hot or "burn" at 1,5V. Good that it's not your mac and only a cheap 775 Platform.
Now this CPU should show up as 3,4GHz with a new Vcore (CPUz does show wrong values for me, but the bios showed the right "modded" default value).
Only if the CPU is still stable, you can change the CPU in the Pro 3.1.
The System Information dialogue will not show the correct FSB but tools like CPUz (only tested in Windows) do show up an FSB of 400MHz.
Both 771 e5440 cost me around 25€ and a 775 board is around 30€ (you can sell it with a modded xeon for more afterwards).
