Dual 600MHz Cube

[hoi polloi]

I've wanted to try this for quite a while now as it combines a few of my interests: the Cube, dual G4 computers, and hardware mods.  So the dual 450/500MHz CPU cards from the apple towers will fit in a cube, but it's pretty rare to see these go past 550MHz or so when overclocking.  Also, they use the 7400 chip so they take some power and start to stress the power supply components.  The dual 533MHz CPU is a later version that uses 7410 chips.  These are nice because they can often go to 600 or 650MHz and they use less power.  However, apple flipped things around so they don't fit a Cube anymore.  The single CPU cards are almost the same and make a nice drop in upgrade for cubes, but the duals are almost a mirror of the earlier cards:

So since I had both cards, I pulled all 4 chips and put the 7410 chips on the board that fits a cube, adjusted voltages and pll settings:

I installed it in a cube and it works well:

I recorded some overall power numbers along the way:

500MHz 7410 idle 28.8w max CPU 38.4w

dual 450MHz 7400 idle 40.8w max CPU 62.4w

dual 600MHz 7410 idle 38.4w max CPU 55.2w

 

[olePigeon]

Holy cow, nice job.

What about a dual 1GHz from a QuickSilver?

 

[dlv]

Wow, very cool!!  

 

[Bolle]

What about a dual 1GHz from a QuickSilver?

That one uses 7455 chips that take way more power.

Also they used the same "flipped around" CPU board that won't fit the Cube easily (or at all?)

On top of that those cards generate the VCore from a seperate 12V supply. Drawing that much from the tiny 12V line in the Cube would probably instantly kill the VRM.

 

[Franklinstein]

The only chip that is pin-compatible with the 7400/7410 is the original 750, and that would be a step backward. All of the later 74xx series chips are different either because they use on-die L2 cache or they have on-die L2 plus external L3 cache; in either case the pins are different not only from each other, but from the preceding 7400 models. Also, as mentioned, the later chips have a different and greater power requirement that would need addressed even if you could physically mount them. So it looks like the maximum speed with a 7410 is going to be about 600MHz.

 

[beachycove]

How did you “pull” the processors? 

 

[Bolle]

I would guess hot air - at least that’s how I do those kind of things (together with an infrared preheater and lots of flux)

Then you just pick them up once they start to swim.

 

[hoi polloi]

How did you “pull” the processors? 

They are soldered to the PCB.  Look for 'bga soldering' on youtube to get an idea.  Here is a swap on a 12" powerbook:

From here:

https://68kmla.org/forums/index.php?/topic/27873-almost-fastest-powerbook-ever-and-more-to-go/&page=3

As others have mentioned, the 7455 chips don't really work well in a Cube.

 

[olePigeon]

I guess not unless you buy the aftermarket upgrades with the beefier power supply, but they usually include a loud fan that defeats the purpose of a silent cube.

 

[hoi polloi]

I suppose there are not many people interested in the Cube anymore.  There used to be a forum dedicated to it, but it has been gone for a while.  Anyway, I thought I'd share another Cube project of mine.  I have an extra logic board (no plastic enclosure) that I want to use as a small desktop.  About half of the Cube volume is the full size CD compartment and the 3.5" hard drive.  Eliminating these shrinks the computer significantly.  I have a dual G4 card that will run at 2GHz with proper cooling, so I made a heatsink and I've been bench testing things:

So the plan is to make a wood enclosure with ducting for the heatsink and mount points for everything.  A 2.5" drive or msata will fit between the video card and logic board.  I think one large fan at low speed on one end that runs continuously with the two small fans on a temperature controller at the other end will work.  The 7447 with DFS and nap has quite a range of power consumption.  I have a pretty simple controller that works with a thermister.  Does anyone have a suggestion for a better way to control the speed of the two small fans?

 

[Trash80toHP_Mini]

Love that heatsink, did you machine that yourself or lop off two standard sinks to mate them up in a custom config?

Don't you dare cover up that beauty with wood! In this case, clear plexi is definitely called for IMO. Very, very cool! :approve:

 

[Byrd]

Nice work - did you have to relocate the copper coil on the dual G4 card, or did you modify the stock Cube heatsink?  I didn't know the DA dual G4 was completely different to the Sawtooth dual G4 - I bought a DA dual 533 years ago with intention of doing the same mod, but always thought it was an easy enough fit.

A custom G4 Cube would be rather special - you might as well put in a massive GPU (flashed Radeon 9800 for example) in there and power all off a big external PSU - perhaps check out some of the newer ITX cases out there

 

[hoi polloi]

Nice work - did you have to relocate the copper coil on the dual G4 card

There is room for the inductor on the power supply to lay flat, so I re-wind them like this: