Sonnet G4 1.2 GHz Upgrade overclocking: Trying to crack the CPLD

[EmilioCube]

I recently got my hands on a very cheap 1.2 GHz Sonnet upgrade and as the chip on it is a RX1250PF I guess I can easily overclock it to 1.4GHz.
Also laying around is a non-working 1 GHz upgrade also from Sonnet and so I used that to compare resistors.
This is what I found out, differences are as following:

R20 and R33, closed on 1.2GHz but open on 1GHz
R28, open on 1.2 and bridged with "5R1" on 1GHz

R11-R15 (99% sure these are the PLLs): 01000 on the 1 GHz board, 10101 on 1.2 one.
Both are 100mhz bus ones as they work in my Cube, but what makes me wonder is that the data sheet says something entirely different for the 10x and 12x configs: 10101 for 10x and 10111 for 12x.

So is there anyone knowing more about Sonnets PLL configs and how I need to resolder them to change the clock speed?
Thanks in advance!

 

[LightBulbFun]

So is there anyone knowing more about Sonnets PLL configs and how I need to resolder them to change the clock speed?
Thanks in advance!

Sonnet CPU's like that have their PLL multiplier controlled usually by some sort of CPLD or the such like,

there might well be separate resistor straps that tell the CPLD what speed the CPU is and thus what multipliers to set the CPU too, but there wont be direct PLL resistors on the board im afraid

this is because sonnet wanted their CPU's to be completely plug and play/"smart" and work in both 100Mhz and 133Mhz bus speed systems without the need to change any jumpers etc, so they use a CPLD or such to set the multipliers on the fly

in theory if you wanted to brute force it, you could de-solder the CPU and beep out where all 5 CPU PLL's (PLL0 PLL1 PLL2 PLL3 PLL4) go from their respective pads on the Ball grid array, onto the PCB and then remove resistors/cut the traces to isolate them and install your own PLL pull up/pull down resistors but this is fairly involved and again quite brute force

 

[Needleroozer]

I recently got my hands on a very cheap 1.2 GHz Sonnet upgrade and as the chip on it is a RX1250PF I guess I can easily overclock it to 1.4GHz.
Also laying around is a non-working 1 GHz upgrade also from Sonnet and so I used that to compare resistors.
This is what I found out, differences are as following:

R20 and R33, closed on 1.2GHz but open on 1GHz
R28, open on 1.2 and bridged with "5R1" on 1GHz

R11-R15 (99% sure these are the PLLs): 01000 on the 1 GHz board, 10101 on 1.2 one.
Both are 100mhz bus ones as they work in my Cube, but what makes me wonder is that the data sheet says something entirely different for the 10x and 12x configs: 10101 for 10x and 10111 for 12x.

So is there anyone knowing more about Sonnets PLL configs and how I need to resolder them to change the clock speed?
Thanks in advance!

View attachment 2405486



View attachment 2405487

If you look up the numbers on top of the chips, you’ll find that U3 is an SC1182B switching regulator and has five VID pins (upper right side, pins 18 to 22) to configure its output voltage, which is what I suspect R10-14 do. You can probe this out with a multimeter to confirm that, luckily without needing to desolder anything.
See page 6 of the datasheet for a table of output voltages.

https://static5.arrow.com/pdfs/quickdata/sem/sc1182b.pdf

The Xilinx IC, U5, is indeed a CPLD like @LightBulbFun hypothesized. I don’t see any PCB traces running from the R20,R21,R33,R34,R35,R40 complex to the CPLD, but it’s entirely possible they run on an inner layer. You could determine whether they connect to the CPLD or not using a multimeter as well.

 

[EmilioCube]

this is because sonnet wanted their CPU's to be completely plug and play/"smart" and work in both 100Mhz and 133Mhz bus speed systems without the need to change any jumpers etc

Aah, thats how they achieved that, thanks. I always wondered how Sonnet managed that and Apple modules always have to be modified.

de-solder the CPU and install your own PLL pull up/pull down resistors

ez


just kidding I guess I will never be skilled enough for that

You could determine whether they connect to the CPLD or not using a multimeter as well.

I knew "thanks in advance" was right. Ill give it a try.

 

[lolof]

I would say J3 is the jtag for the cpld.
Maybe it can be read and be modified.
I don’t know if this could help to adjust the frequency…. If I had a card not in a cube, I would give it a try to dump the Xilinx….
That’s easy to do if it’s not read protected.
Than it could be maybe possible to let think the sonnet card (with a modified code in the cold) that the bus is a 133mhz one and have the cpu running 33% faster ?
Though, no idea if the cpu would be stable at 1.6…..

 

[EmilioCube]

Definitely not. Not even the average 1.42GHz 7455 chip that was an Apple exclusive ran stable at more than 1.5GHz.
What I want to modify are

R11-R15 (99% sure these are the PLLs): 01000 on the 1 GHz board, 10101 on 1.2 one.

Its probably safe to say that if I set the resistors fom the 1.2GHz board to the 1GHz board setting it would also run at 1GHz. I am just too stupid to find a data sheet to determine which PLL config I need for 1.3 or 1.4GHz. Maybe someone else finds one.

 

[EmilioCube]

Thats all what I found but that Data sheet dies not say anything about frequencies... https://www.datasheetspdf.com/datasheet-pdf/1088460/XC9536XL.html
XILINX XC9536XV VQ44A is what Im looking for.

 

[EmilioCube]

Better idea... what about finding a hi-res picture of the 1.4GHz version of Sonnets upgrades and just use that to find out the resistor layout for 1.4GHz?
This is the best picture I could find (from Newegg):

The photo barely allowed me to find out that Sonnet used the same XILINX XC9536XV VQ44A.
There are no R11-R15 to find, but R15-R19 (at the same position where R11-R15 were on the two lower-end upgrades) which are 00101.


I just found another 1.4GHz upgrade with a different PCB layout: In a video of Daves Vintage Apple Tech I managed to shot this capture. As the board layout looks more similar to the one of the 1.2GHz upgrade so I think this resistor layout (also R11-R15, 10011 instead of 10101) is more trustworthy to try:

To sum that up, I believe it is possible to either
close R11 to go from 10101 to 00101 (Neweggs layout, not so trustworthy) or to
swap the 0 Ohm resistor from R14 to R13 to go from 10101 to 10011 (more trustworthy)
to overclock the card to 1.4GHz.

Am I talking nonsense here? I would love to try that out but dont want to do something very stupid by shredding this expensive upgrade.

 

[ervus]

I would give it a try to dump the Xilinx….
That’s easy to do if it’s not read protected.

If this is something you could do, it would definitely be useful. I doubt there are very many people with the skills and equipment to do it. Reading the program on that chip could tell us all the possible settings. My approach would be to remove that chip and throw it away, then control the settings myself...

 

[EmilioCube]

So I guess I wait for @lolof s results?

 

[lolof]

If it’s not protected, it’s just a matter of powering the cpu card somehow and connect the jtag correctly. The jtag pins order can be found with a multimeter and the Xilinx datasheet.
Read the chip with impact software using something like this device.

Waveshare XILINX JTAG Download Debugger Compatible XILINX Platform Cable USB FPGA CPLD in-Circuit Debugger Programmer

Waveshare XILINX JTAG Download Debugger Compatible XILINX Platform Cable USB FPGA CPLD in-Circuit Debugger Programmer

amzn.eu

I could have tried to do it but I just finished to put my cube all together…. The next time I will take it apart, I will if nobody did it.
But then, you have to find someone who can do something with that. It’s the hardest part….

 

[EmilioCube]

Or just try

swap the 0 Ohm resistor from R14 to R13 to go from 10101 to 10011 to overclock the card to 1.4GHz

? Or is the risk of damaging something too high?

 

[indibil]

In case it helps in the research, this is a photo of a Sonnet Encore ST 800 that I have.

 

[indibil]

Hello, a friend lent me his OWC 1.4GHz for a few days, which is almost identical to a Sonnet Encore ST 1.4GHz. I would say that they were manufactured by Sonnet, but there is a small difference: a soldered switch where the Sonnet one doesn't have one.

Although a 4-position switch would fit, it only has a 2-position switch. As far as I can see, it's a 1.3GHz model that OWC sold at 1.4GHz. I'm going to name switches 1 and 2 in yellow, not the ones indicated on the switch itself.

It came with switch 1 set to ON (lowered), and if I raise it, as if there were no switch, just as Sonnet sold it, the computer drops to 1350MHz (Tested on a GE). So if I leave switch 1 raised and set switch 2 to ON (lowered), the computer boots at 1.5GHz!!! I've tried lowering both and it freezes on startup; it must be a higher speed. The shame is that lower versions of Sonnet don't seem to have those pads.

This is the photo of the Sonnet 1.4GHz that you published, without the switch

It appears that some bypass of Sonnet's auto-PLL is possible.

edit: It seems that those PADS are also available in the Sonnet versions with MC7447


.

 

[ervus]

With hardware, it's pretty funny to see pointless layers of complexity to do something simple. With software, that Rube Goldberg contraption would only be the start.

 

[Nullcaller]

It came with switch 1 set to ON (lowered), and if I raise it, as if there were no switch, just as Sonnet sold it, the computer drops to 1350MHz (Tested on a GE). So if I leave switch 1 raised and set switch 2 to ON (lowered), the computer boots at 1.5GHz!!!

It's interesting what this switch was supposed to do and why it's there, lol. My mind immediately jumps to the 2000s thing of "press this patent-pending trademark-registered Turbo Button to make the computer go FAST"

 

[EmilioCube]

Hello, a friend lent me his OWC 1.4GHz for a few days, which is almost identical to a Sonnet Encore ST 1.4GHz. I would say that they were manufactured by Sonnet, but there is a small difference: a soldered switch where the Sonnet one doesn't have one.

View attachment 2529430
View attachment 2529429

Although a 4-position switch would fit, it only has a 2-position switch. As far as I can see, it's a 1.3GHz model that OWC sold at 1.4GHz. I'm going to name switches 1 and 2 in yellow, not the ones indicated on the switch itself.

View attachment 2529431

It came with switch 1 set to ON (lowered), and if I raise it, as if there were no switch, just as Sonnet sold it, the computer drops to 1350MHz (Tested on a GE). So if I leave switch 1 raised and set switch 2 to ON (lowered), the computer boots at 1.5GHz!!! I've tried lowering both and it freezes on startup; it must be a higher speed. The shame is that lower versions of Sonnet don't seem to have those pads.

View attachment 2529432

This is the photo of the Sonnet 1.4GHz that you published, without the switch

View attachment 2529433

It appears that some bypass of Sonnet's auto-PLL is possible.

edit: It seems that those PADS are also available in the Sonnet versions with MC7447


.

Whoa, nice findings! I like the idea of overclocking with switches. Sad that my card does not have these pads as it’s a 7455…

 

[Lord Blackadder]

I believe I have the same model of OWC Mercury Extreme 1.4 Ghz 7455-based card as @indibil. It's been chugging away for the last 20 years in my upgraded Digital Audio G4. I'm not going to mess with removing the heatsink, but can confirm that my switches are set the same as in their photo.

Also, based on OWC's archived pages I believe this is their '2nd generation' G4 upgrade, which correlates with these installation instructions. Note that only two switches are referenced in this table, and on a 133Mhz bus PowerMac G4 your speed options with the 1.4 Ghz part are 1333, 1400, 1467, and 1533Mhz. Going by the label on the switch itself mine is set with switch 1 on and switch 2 off, matching the advertised speed of 1.4GHz.

Note also that the 1.2 Ghz upgrade clocks up to 1333Mhz in this chart. I believe Both OWC and Sonnet used a 1.0Ghz 7455 on their 1.0GHz and 1.2Ghz upgrades, while the 1.4 Ghz upgrade was a 1.4Ghz-clocked 7455...but it's been years since I futzed with this, so I am not sure about that. I do recall that some upgrade cards were factory overclocked, others were not. I doubt that the overclocked ones have much (if any) further overclocking potential.

It's fun to play around with these, but I admit I have no interest in pushing mine beyond its factory settings. My machine, with this CPU, three HDDs, SATA card, 1.5GB memory, and a GeForce 6800GS flashed to Mac Edition 6800GT, is already running quite hot and probably taxing its aging power supply as it is. If I need more PPC power than that I'll boot up my PowerMac G5, which will outperform the G4 even if the latter had an additional 5-12% overclock. This was my main machine for years and I have been giving it a comfy and easy retirement (I use it for reading Zip discs and playing the odd old game).

Upgrade cards are so much rarer than the Macs themselves, I do wish I'd bought a second one when their value bottomed out maybe ten years ago or whatever (and don't get me started on what the 68k mac 68030 and 68040 CPU upgrades are worth now - holy cow!!!!). The G4 upgrades are going for about half original MSRP on the auctions these days, which is still a lot...you can get a working PowerMac G4 MDD for substantially less than that!

Anyway, good luck with your project. I suppose you still need some really good photos of a Sonnet-branded 1.4Ghz upgrade with the purple (not green) board to really find out what you're after.

EDIT: what about this one in an old MR thread? You can see the 1.4Ghz (purple) Sonnet upgrade has a subtly different board layout from your 1.2Ghz board, and seems to be using a 1.4Ghz 7455B. This would track with the contemporary advertisements.