I had a Slackware64 13.37 desktop system where suspend worked flawlessly. After I did a hardware upgrade (mobo-cpu-ram), and made a clean install, suspend doesn't work, nor within KDE, or via the command 'pm-suspend'.

What do I mean by "desn't work":
In my previous system everything seemed to be turned off, the tower's power led was blinking and when I pressed the power button the machine resumed as expected. After the upgrade, I choose "suspend to RAM", the screen goes off (as expected), but the machine remains on (at least you can hear the cpu fan spinning), the power led remains on, nothing can wake the machine back from sleep, so I have to hard-reset.

I use the same NVIDIA card as before (I read somewhere that often it has something to do with the graphics card), with the same proprietary drivers (the latest). My system is vanilla Slackware (no custom kernels or anything). Switching between huge kernel and generic with initrd doesn't change a thing. Maybe it has something to with RAM? I upgraded from 2GB DDR to 8GB DDR2. Or a kernel issue?

It would help if you tell us which motherboard is in the machine. I often found that the settings for the suspend-mode in the BIOS are set to S1 instead of S3 by default. This would explain why your machine isn't turning off, but sadly not why it isn't turning on when it should be.

Hi, sorry I didn't mention that... Motherboard is "Asus M2N-SLI Deluxe" and I've already checked the suspend mode. It defaults to S3, and I've tried the other two available options ("S1" and "S1 & S3") just in case (didn't know the difference between suspend modes). So, yeah the problem remains.

I would have a look for clues in the pm-suspend log on /var/log/

Guys, thank you very much for taking the time. In the end, the problem was solved by upgrading my BIOS. Suspend works flawlessly now.