Under the heatsink of an Encore G4/ZIF

Fami7455

macrumors member
Original poster
Jul 6, 2019
38
65
The computer (The network)
So, a couple of months ago I managed to get my hands on a Sonnet Encore G4/ZIF 1GHz, possibly the fastest G4 upgrade for the PowerMac G3 and "Yikes!" G4.

I couldn't find any pictures of how the card looked under the heatsink on the Web, so I decided to take some and post them here, as this seems to be the best place to put them:
DSC03756.JPG
DSC03759.JPG
Some non-documented findings:
-The card uses an XPC7455, which gets detected properly by all utilities (Including CHUD) if the Sonnet extension is loaded. OFW detects it as a "60x"
-The CPU multiplier seems to be set via the CPLDs, there are no PLL resistors that I can see. It's permanently set to 15x
-The CPLDs installed between the CPU and the system bus can only work up to 66MHz officially. This means the card underclocks the bus when installed in a B&W or a "Yikes!".
-I managed to overclock mine to 1125MHz by setting a 75MHz bus speed. I know my G3 can do up to 83MHz (Tested with a ZIF G4 from a "Yikes!"). Anything above that slows down memory accesses due to the bus translators not being able to keep up, but doesn't cause crashes. In fact, the CPU score goes up in most benchmarks!
-The L3 cache runs with a 1:4 divider. That's 250MHz in the stock configuration.

If you guys want any more info just ask. One of the reasons why I got this upgrade was just to document it a little better.
 
Last edited:

velocityg4

macrumors 601
Dec 19, 2004
4,599
1,184
Georgia
That's a neat old upgrade. I had many Sonnet upgrades back in the day. My favorite was that they managed to shove a G3 into an L2 Cache slot in the Performa 6400.

Too bad upgrade cards aren't possible anymore. If they were I'm sure Sonnet would have figured out how to cram a modern Xeon in the Mac Pro 4,1 and 5,1.
 

LightBulbFun

macrumors 68020
Nov 17, 2013
2,127
1,941
London UK
So, a couple of months ago I managed to get my hands on a Sonnet Encore G4/ZIF 1GHz, possibly the fastest G4 upgrade for the PowerMac G3 and "Yikes!" G4.

I couldn't find any pictures of how the card looked under the heatsink on the Web, so I decided to take some and post them here, as this seems to be the best place to put them:
View attachment 847148
View attachment 847149
Some non-documented findings:
-The card uses an XPC7455, which gets detected properly by all utilities (Including CHUD) if the Sonnet extension is loaded. OFW detects it as a "60x"
-The CPU multiplier seems to be set via the CPLDs, there are no PLL resistors that I can see. It's permanently set to 15x
-The CPLDs doing the 60x bus<->MaxBus translation can only work up to 66MHz officially. This means the card underclocks the bus when installed in a B&W or a "Yikes!".
-I managed to overclock mine to 1125MHz by setting a 75MHz bus speed. I know my G3 can do up to 83MHz (Tested with a ZIF G4 from a "Yikes!"). Anything above that slows down memory accesses due to the bus translators not being able to keep up, but doesn't cause crashes. In fact, the CPU score goes up in most benchmarks!
-The L3 cache runs with a 1:4 divider. That's 250MHz in the stock configuration.

If you guys want any more info just ask. One of the reasons why I got this upgrade was just to document it a little better.
thank you for taking your time to document your findings so far :)

to people like me who like to tinker with this sort of stuff, its very valuable info :)

its interesting that you say the CPLDs are doing a 60x bus to Max bus translation, I knew the 745x had issues with the MPC106 Memory controller

I figured sonnet would have just run the CPU itself in 60x mode to avoid any complication translations

I wonder if these have user settable PLL resistors like the 700Mhz-1Ghz Sonnet Crescendo

a chap on the 68kMLA upgraded his to a 1.4Ghz 7455 from a MDD, and made a 1.4Ghz G4 PowerMac 9600 which was quite cool to see :)

(although sadly the L2 cache vanished, we suspect it might be because the 800Mhz upgrade he started with was setup for a 7450 and not a 7455)
 
  • Like
Reactions: Fami7455

Fami7455

macrumors member
Original poster
Jul 6, 2019
38
65
The computer (The network)
That's a neat old upgrade. I had many Sonnet upgrades back in the day. My favorite was that they managed to shove a G3 into an L2 Cache slot in the Performa 6400.

Too bad upgrade cards aren't possible anymore. If they were I'm sure Sonnet would have figured out how to cram a modern Xeon in the Mac Pro 4,1 and 5,1.
My favorite has to be the G3 upgrade for the 6100. Cramming a G3 inside a first generation PowerMac with a non-upgradeable CPU is just an impressive feat.
wow lucky you, I've been trying to find one of this for years!! Nice pictures :)
I spent quite some time looking for it, too. And I had to go through some hurdles to get it shipped to me. That was not fun.
thank you for taking your time to document your findings so far :)

to people like me who like to tinker with this sort of stuff, its very valuable info :)

its interesting that you say the CPLDs are doing a 60x bus to Max bus translation, I knew the 745x had issues with the MPC106 Memory controller

I figured sonnet would have just run the CPU itself in 60x mode to avoid any complication translations

I wonder if these have user settable PLL resistors like the 700Mhz-1Ghz Sonnet Crescendo

a chap on the 68kMLA upgraded his to a 1.4Ghz 7455 from a MDD, and made a 1.4Ghz G4 PowerMac 9600 which was quite cool to see :)

(although sadly the L2 cache vanished, we suspect it might be because the 800Mhz upgrade he started with was setup for a 7450 and not a 7455)
I thought the 7455 didn't have the 60x bus compatibility mode, that's why I thought they were doing a MaxBus translation. Maybe they're just there for flipping the ZIF pins around to allow for installation in different orientations. I'll correct this on the OP.

No PLL resistors I could find, I think the multi is set via CPLDs, like most other Sonnet cards.

Yup, I saw the 68kMLA thread about the 1.4GHz 9600. Absolutely crazy. What I'd give for a 9600. They seem to be pretty much unobtanium here. It'd be fun to see if one of these Encore/ZIF cards worked in one of them with an XLR8 CarrierZIF.
 
  • Like
Reactions: LightBulbFun

LightBulbFun

macrumors 68020
Nov 17, 2013
2,127
1,941
London UK
It'd be fun to see if one of these Encore/ZIF cards worked in one of them with an XLR8 CarrierZIF.
I believe someone on the 68kMLA tried, but sadly it did not work

I do have a XLR8 Carrier but no Sonnet 7450/7455 ZIF sadly or id give it a try myself as well :)


I was fortunate enough to bag myself a 9600 a while back which you can read about here https://forums.macrumors.com/threads/powersurging-to-mac-os-x-10-5-8-power-macintosh-9600-fun.2144305/

id like to do more with it, but I need to get some more RAM for it first!


its hard to see in your picture, but is sonnet using a 1Ghz rated 7455 or are they overclocking a lower speed part slightly?

(I have wondered if a 7457 CPU would work on one of these upgrades :) )
 

Fami7455

macrumors member
Original poster
Jul 6, 2019
38
65
The computer (The network)
I was fortunate enough to bag myself a 9600 a while back which you can read about here https://forums.macrumors.com/thread...os-x-10-5-8-power-macintosh-9600-fun.2144305/
Quite impressive.

I've been using the Leopard image you posted on that thread on my Beige G3 (Which has the encore/ZIF in it) for quite a bit.

its hard to see in your picture, but is sonnet using a 1Ghz rated 7455 or are they overclocking a lower speed part slightly?
Unfortunately I wasn't able to get the marks on the chip to show on the pictures, but it is in fact rated for 1GHz.

(I have wondered if a 7457 CPU would work on one of these upgrades :) )
That would be pretty neat, unfortunately I lack the equipment to perform such a modification.
 
  • Like
Reactions: LightBulbFun