I've had similar problems installing win98 on fast hardware. Go for the oldest drivers you can find - for everything. I'd also get rid of the SSD. It offers almost no performance boost in 98.

Make sure you install the intel chipset driver first, then the sata driver. Also make sure that system resources are set to auto in bios, and PnP OS is also enabled in BIOS. These should normally be disabled on old machines for compatibility with ISA and legacy devices, but your machine requires them to be on to work correctly. Go for an older nvidia driver as well. Oh and always install DX before installing the video card and sound card driver.

What sound card are you using? If it's a creative CT4810 or similar (Sound blaster PCI128) get the oldest driver from the creative website. That's how I got it to work on my A64 voodoo 2 sli rig.

I'm amazed You can install Win98 on that. First of all I would suggest going into the bios and turning off anything that You are not using, com ports, parallel port, onboard sound, Network, etc.
The problem with Win98 on a more modern motherboard is the lack of IRQ's vs Winxp, 15 against 23 or 24.
The later Nvidia Win98 drivers give terrible performance in games, they didn't care about optimisation at that point.

I assume You have installed the Intel Chipset INF? For the sblive I would suggest aiming the windows driver update at the cdrom folders rather than running it from the cd.

If You are going to get rubbish performance You may as well just put winxp on it, but it would still be a very powerful Win98 gaming rig if You can get it sorted.

I've turned off everything I don't use in bios. I'm thinking about skipping IDE alltogether and go with a S-ATA DVD instead if that works, and just disable IDE.

I will try to find older drivers for graphics card and sound card.

The idea was to create the most powerful Win98se machine possible, without doing "hacks". In theory the above setup should work since everything has official Win98 drivers. I already have the most powerful WinXP machine possible 😀

I've used an Asrock board in this build: 10 Reasons for a Pentium 4 Windows 98 DOS Retro Gaming PC :)

Your drivers are here:

http://www.asrock.com/mb/Intel/775i65G/?cat=Download&os=98

I loaded INF and USB drivers. Didn't use Ethernet, had it disabled in BIOS, as well as the sound card.

While I was able to use SATA HDD and IDE optical drive fine, all you need to do is copy the Windows 98 SE installation folder onto the hard drive (I always put it in C:\W98), then run setup from there.

Can you take screens of the BIOS options, specifically for the SATA / IDE controller?

I know that the IDE / SATA controller must be in legacy mode. Enhanced mode will not work with Win9x.

I used enhanced mode first time around, but maybe it was that which made everthing feel buggy.

I installed Win98 from the HDD last night, but it was even more buggy and wouldn't finish the installation until a booted in safe mode and installed Intel inf in between restarts and after that it kind of finished the installation, but it's extremly unstable now and won't start every time. The DVD is still not visable even though it's on S-ATA now. Unfortunatly I installed using enhance mode so I will try another installation tonight with compatible mode from the beginning.

To be continued...

Oh, I also had issues with SSD. Try a standard platter drive. It has to be under 120 GB ideally.

Also use the Win98 install option "setup /p j" to enable ACPI support.

I'm building this exact machine now - ASRock 775i65GV (G/A 1.05) with a GeForce Ti4600. In BIOS you'll want to go to Advanced -> IDE Operate Mode -> Compatible Mode. In my case I had only a DVD reader on Pri slave and SATA 0 so I disabled the IDE channel.

Worked OK, I had some issues with VXD files loading after, but I think that may have been a runaway "next" click for a driver location.