This is probably like , "Well, duh!" for everyone else, but it surprised me...

I thought I'd post just in case it helps someone else.

Anyway, I have an ASRock Conroe945PL-GLAN board with a Pentium D 820 cpu - setup for linux and OSX (JaS 10.4.7)

So, this setup works well under linux, but would often lock-up oddly in OSX unless I set cpus=1...
With cpus=1 it was solid as. So I've tried all manner of workarounds with no joy until today.

I want the machine to be stable, so I had no overclocking on, pretty much everything was set to the bios recommended defaults - in particular CPU host frequency and DRAM frequency were both set to AUTO, which is recommended by the manual.

Now, the CPU has a 800MHz FSB, so the CPU speed is auto-detected as 200MHz, whilst the DRAM I have is DDRII533, so it auto-detects at 266MHz (anybody spotted where I'm going with this?)

Anyway, I manually set both to 200MHz and now it runs just fine *without* cpus=1. The linux boot seems unaffected.

So, I guess the RAM is "under-clocked" now, but who cares, the system is stable. It's a definite win.

For the record, the rig is:
ASRock conroe945PL-GLAN (945PL Northbridge, ICH7 Southbridge)
Pentium D 820
512MB no-name DDRII533 RAM
no-name ATI X300 graphics
Realtek 8139 PCI NIC
160GB Maxtor PATA HDD
Lite-On DVD burner (maybe a 1633? can't remember)

Everything works except the audio, which I never bothered with since the machine was flaky - now it's good I'll need to patch that up too, I guess.
And I had to patch the display resolution in Boot.plist, of course, but it seems good, CI and QE both reported as supported.

The only other oddity is I disabled the on-board LAN (Realtek RTL811B) 'cos my hacked up linux kernel doesn't like it, and fitted a cheap 8139 instead, since they work with, like, everything...

Just about every part was picked on the basis of price (i.e. cheapest the store had in stock) rather than compatability, or else it's just bits I had lying around. It's turned out OK.
So, seems good now, and tests out a lot faster than my aging 2002 Quicksilver DP G4

Hope someone finds this useful...

I have the G version (GMA950).

I had movie stuttering issue with 2 cores (no issue with 1 core). It was resolved with a BIOS upgrade (1.0 to 1.1).

Same here.

Hmmm...I don't understand the workaround here, but if it works that's fine. Did you try BIOS upgrade?

Good setup. I would add more RAM tho'.
In another 2 years time, you would have to upgrade or build another system anyway, so I would have gone part picking based on price too.

Really, what I'm saying is that I had to stop the BIOS auto detecting the RAM and CPU clock speed, and maually set them to be the same. That works, but to me it hints at some sort of underlying synchronisation issue... More on that topic later...

In other news...
- The BIOS was already at 1.1 when I got the board, and I have since flashed it up to 1.2. Made no difference. But alwyas worth trying, I reckon.
- Yes, I do need more RAM, but the 512 was enough to get started, and budgets are budgets...
- Also planning to bung in a SATA drive now the machine is working, at least for the linux partiton, if not for the mac. Cash permitting.

Now, about synchronisation issues... I'm using MouseLocator to hide the mouse-tearing that the ATI graphics suffers from, and that's just fine. Generally, I use it with the "blank" PNG (posted elsewhere in this forum) and that's fine. However, there is also a "shadow" PNG (emulates the OSX style mouse shadow effect) and it looks real good.

But... If I use that shadow PNG in cpus=1 mode, everything is smooth - if I use it in 2-cpu mode, then when the mouse moves, there are TWO cursors on the display (until it stops moving, of course).

So in some way I don't get, the screen refresh is synchronised differently when 1 cpu is running to what it is when 2 are running. And that does seem very odd to me...

I wonder if my old dual Quicksilver does the same? There's something I should try...

Well, turns out it does - but the two images are so close together it's real hard to tell.

On the intel box, they are a *long* way apart, so something is different...

Anyway, this is way off-topic for the thread, so I'll shut up now!