Report: Houdini & Clock-chipping

From: (Eric "the" Hsu)
Newsgroups: comp.sys.mac.hardware
Subject: Report: Houdini & Clock-chipping
Date: Wed, 09 Nov 1994 12:53:58 -0700
Organization: U.C. Berkeley Math Dept.

To Houdini & Clock-chipping fans:

Recently people were asking about how the Houdini works with a
clock-chipped Mac and actually being clock-chipped, so here is my report
on various hot-roddings. For those of you to impatient to read the whole
post, the summary is: 
You can replace your SX/25 with a DX2/66 and run it at 66MHz with a test
clip, exactly the same kind as you use to bump up Mac CPU's. Also,
Houdini's will work in a clock-chipped Q610 (30MHz), but if you use both
the DX/2 and a over-driven Mac CPU, you may get heat problems.

Now for the full report:

(1) I have a Quadra 610 w/ a Houdini Card. The card has a 4MB SIMM on it.
I had already popped the 486SX-25 out and popped in a 486DX2/66, which ran
quite well at 25 * 2 = 50 MHz. I put a fan on the 486 because it was
running extremely hot. 
As noted in previous reports, I did not install the appropriate shunts,
because I like to live dangerously and I don't really use the FPU (yet...
I will soon, though, so I can give a better report later on this).

(2) I got a special handmade "low-profile" test clip from Output Enablers
to bump the Q610's 25MHz clock to 30MHz. This test clip worked great (with
the Houdini uninstalled), although it was a pain in the rear to get it to
clip right on the oscillator chip. I ended up bending the clip pins
slightly to make it easier. The 040 ran quite hot and I put a fan on the
040 (OE sent me a fan too).

(3) I tried to put the Houdini in while keeping the 040 clock-boosting
test clip installed. Because of the placement of the 486 on the Houdini
and the Mac's 040, I had to shift the fan on the 040 very close to the PDS
slot so the two fans didn't bump. As you might have guessed, the Houdini
and the 30MHz Quadra booted up and worked fine... at first. 

(4) In fact, the faster Quadra CPU made the Houdini faster! Disk access
was noticibly improved. From the wonderful FAQ (which is on before you send me e-mail asking), I gather
that a bare Houdini has to share memory cycles with the host CPU. When you
pop in a SIMM, the Houdini can talk to its own memory, except for calls to
the BIOS (is the BIOS sitting in PC Setup's memory?), which only
significantly happens during disk access. But still, disk access perked up
a lot.

(5) HOWEVER, there were intermittent malfunctions with time. In
particular, the keyboard/mouse would stop working and the machine would
lock up during serial port activity. When I inspected the CPU's, they
actually seemed reasonably cool, but a number of support chips on the
Quadra motherboard were really quite toasty. My guess is that whatever
chip controls the ADB bus or serial stuff overheats. In fact, I'm pretty
sure this is the right idea, because I ran the 50 MHz Houdini+30MHz Q610
with the cover off and a (big) fan right on the motherboard, and it ran
well for hours.

(6) So, I was disappointed that I couldn't reliably run the DX2 Houdini
with the  sped-up Q610. In fact, the 25 -> 30 MHz boost is not all that
impressive on the Mac side. I needed Snooper to convince me the boost had
occurred, actually. Since the Houdini and the Mac have identically cased
oscillators, I tried the test clip on the Houdini. It worked great. It was
kind of funny to see the Houdini running at 15 MHz (clock-doubled, no
less!). Shades of the old PC-XT days!

(7)  I got a 66MHz can-style oscillator (from Computer Source on
University in Berkeley, in case you're curious) for $4.50 and put it in
place of the 15MHz crystal from the Output Enablers test clip. The Houdini
booted on the first try and it's working great. Doom is noticebly
smoother, and NHL Hockey seems to be putting in a few more skating
details. Comptest tells me I'm running at 66MHz, and everything's
hunky-dory. If I had been less lazy, I would have just made my own test
clip assembly (the instructions are also on sumex-aim).

Good luck,

Eric Hsu

Final audit
Houdini card             $300   (free to me)
DX2/66                   $200   ($260 to me... I bought it a while ago)
4 MB SIMM                $120   ($105 to me I think)
Test clip + assemblage   $10    ($70 to me... I was lazy and bought from
66 MHz oscillator        $4.50  (you may have to add shipping)

So if you already have a Quadra 610, you can also have a 486DX2/66 for
$620. Of course, no Soundblaster :<, but the sharing of files between Mac
and PC is untouchable.