How stable my AMD 64-bit systems have been

In a comment on a recent entry, Ryan asked me how stable my 64-bit Linux installs have been. The answer is kind of complicated, but the quick summary is that I am happy with the machines and they're stable.

Currently and in the recent past, I have dealt with three AMD 64-bit machines, two using ASUS M2N4-SLI motherboards, and one with a Tyan Tomcat K8E S2865ANRF, and all with 2GB of memory. The M2N4-SLI is a Socket AM2 motherboard, the Tyan is a Socket 939 board (and the motherboard that Sun used, in a modified form, in the first generation Ultra 20s).

The problems I've run into:

• The two M2N4-SLI machines have to use the noapic kernel parameter with current kernels. Without it, the machines lock up solid during boot (just before the kernel would normally print messages about 'PCI: Linking AER extended capability on ...'.)
• one M2N4-SLI has an ATI X800 GT PCIe graphics card. The original Fedora Core 5 drivers for it caused an instant reboot when they started; the current errata drivers are fine. (I don't have an X800 GT in any other machine, so it might be the card's fault, although the Tyan has an X800 GTO and it was fine.)
• the Tyan had a wierd problem where one bit in one word in the middle of memory would periodically wind up flipped in a particular memtest86+ test pass. We swapped the memory and nothing changed, so I opted not to try a motherboard swap and instead assumed that it was some SMM/SMI wierdness in the BIOS and used a Linux kernel feature to make sure that page would never be used.

In general I consider the ASUS problems about par for the course for the early days of a new chipset. And I'm not sure if any of these are exclusively 64-bit issues, since I haven't tried to see if any of them happen under a 32-bit install.

(One caution is that AM2 motherboards are apparently very picky about what memory they will take and how, especially if you want 800 Mhz memory, so sticking to the motherboard's recommended memory parts is highly recommended.)

Machines with 4GB or more of memory may run into various issues, which is one reason I stuck at 2GB.