OS X System Profiler Report @650MHz (active cooled w/Voltage Boost)

" Mike, here are my notes and pictures for the G4 voltage mod.

You can use the PLL table from the G3 voltage drop article. [See Table below-Mike] That's how I labeled the VID registers on the CPU.
The conductive material for the bridges this time was a TechSpray Conductive pen purchased from Frigid North (radio shack).

And I got a vid of the LED front panel mod [shown in one of the images below] on my iDisk at
http://homepage.mac.com/dgiessel/.Movies/G4.mov

Firstly, I'd like to thank BDAqua for sending me this ZIF. I am VERY greatfull for his generosity and thanks to him I have been able to go to X full time as well as get some decent render times. Also, thanks to Mike for putting this up on his webspace and allowing me to use his bandwith :^)

I started with the ZIF at 2.1 volts (stock setting). At this voltage, even 550 MHz was unstable. I eeked the voltage up to 2.3 volts, then 2.4. This gave me stability at 550 MHz and a partial boot at 600. 2.5 volts let me run 600 with a TEC set to pump 35 watts of heat (7 volts) and the pictured HSF with the low profile blue fan (case open). In the quest for more speed (650 MHz), I tried 2.6 and 2.7 volts with the TEC at 12 volts (60 watts) and the black Delta 7k 38 CFM fan on the heatsink. However, 650 MHz was ONLY stable with the window open (-10 C air on the heatsink giving me -40C on the cold side). This was not a viable solution (and one of my hard drives crapped out from the cold air), so I dropped the voltage back to 2.6 and turned the TEC down to 7 volts.

I also replaced the 7k fan with the VERY nice high CFM low noise blue low profile fan. This is the setup that I have used for the last 2 weeks now. Perfect stability. I am able to omit the use of a TEC with the case open or with some of my internal drives unplugged, but with all 3 HDDs cooking in the case, the CPU gets to about 60C and then crashes. With the TEC, max CPU temps are around 30C and case temps are at 40C.

I will be adding a 92mm fan to the top of my B&W case over christmas (the 350 watt PSU I have installed has 2 fans, one 92 and a 80mm exhaust fan, I will relocate the 92 from the PSU to the top of my case, but it will still be controlled by the PSU allowing for thermister RPM controll). I expect case temps to drop to 30C and CPU temps to 20C after this mod.

So I am running 2.6 volts (.1 over the min stable setting for a extra margin of stability), a TEC at 35 watts, and a high density high CFM HSF setup. 600/240 on the CPU with no problems so far.
-David Giessel (aka Tycho)
http://homepage.mac.com/dgiessel "

Notes on Heatsink/Fan Height Limitations w/Apple Cases: The Heatsink/Fan sizes/heights shown in the photos below are too tall/large for the standard B&W G3/G4 PCI systems (Yikes) to allow the case to close. The metal ZIP drive housing below the CDROM drive will hit a heatsink/fan this size when you try to close the case, so be aware of that. (Note the rev 2 B&W G3 heatsinks have trimmed fins on the edge to clear the ZIP drive's metal housing.) I've asked Dave if he's removed/modified the ZIP drive housing, since the case would not close with the heatsink/fan combos shown in the photos below with the standard ZIP drive metal housing intact. (I suspect the case is modified in this area since there's a LCD temperature display in the ZIP bay area per the photo below.)
For Beige G3 owners, also be aware these types of heatsink/fans are too tall. The Beige G3 case presses down even on the stock size heatsink, so taller heatsink/fan combos will not work in the Beige and can cause damage if you don't realize this and try to close the case over a tall heatsink/fan combo.
-Mike

(I asked Tycho if he had modified/removed the ZIP metal bay for clearance and he wrote) My zip bay has been removed and the metal beneath it has been cut away to allow for the heatsink to fit.

The TEC is an ICE71 purchased from www.tedist.com I got the heat sink fan combo at a local computer store (no brand on it).

To change the CPU voltage it is necessary to set the proper code on the VID registers (see RED BOX area in photo below).

2.50 Volt Setting
(he didn't send 2.6V pix, but see Table below)

Machined Notch Details

Pix of Cold Plate

Heatstink/Clip top view
(fan not attached)

Heatstink/Fan Assembly

Front Case View
(with Temperature LCD)

(repeat of previous article info)

In the past, this has been accomplished by moving the 0 kOhm resistors around using fine tipped soldering tools and excellent soldering skills. The prolonged exposure to heat during this process can damage the ZIF and may cause the solder pads to lift off the PCB making it impossible to set the desired voltage. By using electrically conductive paint (rear window defogger repair paint in this case), these challenging and often harmful aspects of voltage tweaking can be avoided (for the most part). [Note: the conductive material used for the bridges this time was a TechSpray Conductive pen purchased from Frigid North (radio shack).]

Step 1: I removed all the 0 kOhm resistors (solder is needed to do this). There was no need to keep track of them or worry about damaging them in the process as they will not be needed later. After they have been removed, I made the remaining solder on the pads as smooth as possible (put a drop of flux or paste on each pad and tap it with a hot soldering iron).

Step 2: I painted over the entire VID block area (the paint dries rather quickly and the area is very small so it is virtually impossible to paint one bridge at a time). Once the paint has dried, I scraped the excess off using an Xacto knife. The final result has 5 bars of remaining paint (one bar connecting each pair of solder pads). I was careful not to let the paint connect horizontally between the pairs of pads (see blue arrow).

Step 3: I set the VID code by breaking the necessary bridges (in the case of my ZIF, the bridge on VID# 4). The measured resistance of the bridges I connected is less than 1 Ohm, so excessive resistance (causing a bridge to be seen as open) should not be a problem.

Related Articles:

• 2nd Article on G3 ZIF Voltage Mods (Illustrated)
• Original Article on G3 ZIF Voltage Mods
• *Reducing Voltage* Article on G3 ZIF (for ZIFs with Stability problems)
• CPU Upgrade Reviews & Related Articles