I suppose you have a K6-3+? A plain K6-3 shouldn't do 550 MHz. Are you running it at the proper voltage?
Is the power supply good? (300W is certainly enough, is it in good working order?)
VIA 4in1 drivers installed?

If you really want to make it stable and want to put some real effort into it you need at first to rule out hardware problems. Try to use a PSU that you are absolutely sure won't be the issue even if you have to install a new one. Check your motherboard for bulging caps, the FIC PA-2013 was manufactered during the early years of the capacitor plague.

I would also use a CPU tool to stress only the CPU heavily, and if you want to have 550MHz use a K6-III+ instead. If the system remains stable after hours of stress with something like Prime95 for instance you can almost rule out the CPU and all the CPU electrical management in the motherboard as cause of the problem.

Try a memory stability test as well, i believe there is a tool with you can boot from a CD and rule out memory problems. It seems that your freezes happen while running 3DMark only and games run fine? After ruling out hardware issues then it should be something software related. AGP stability on SS7 systems was not the best also. Try running newer versions of 3DMark as well.

RAM would be my first suspicion. Are the chips the same model number from the same manufacturer? I would try different RAM, see what happens. At least, take out one and see what happens.

1. Do not disable motherboard cache, you will loose performance,
only disable motherboard cache if you overclock the Front Side Bus to high values,
or want to slow down your PC to a 386 (L1, L2 disabled).

This is how I fixed any crashing problems on my VIA mvp3 motherboard with VT82C586B southbridge.

Windows98SE:
--------------

Install older VIA 4 in 1 drivers e.g. version 4.29, they let you choose the AGP driver.
Install AGP driver in standard mode, not in turbo mode! (no performance get lost)
This fixed system crash problems with nvidia GPUs.
VIA 4-in-1 Drivers 4.29 http://www.k6plus.com/phpBB3/app.php/dl_ext/?cat=5

I also recommend to install this PCI Latency patch for VIA chipsets
"vlatency_v020_beta21" http://vogonsdrivers.com/getfile.php?fileid=8 … &menustate=28,0
alternative link http://www.georgebreese.com/net/dl0/vlatency_v020_beta21.exe
This fixed sound crackling and system crash problems with nvidia GPUs
in combination with SB-Live & Vortex2 soundcards.
It sets the CPU-to-PCI bridge latency timer to "0".

Windows2000 SP4:
------------------

Do not install VIA AGP drivers, they don't let you choose which
AGP driver (standard / turbo) to install and run unstable.
Windows standard AGP drivers run stable for me.

Not tested by me, but should work for Windows2000.
CPU-to-PCI bridge latency timer (NT4/2000/XP)
http://www.k6plus.com/phpBB3/app.php/dl_ext/? … detail&df_id=24
This sets the CPU-to-PCI bridge latency timer to "0".

I hope it will fix your problems too. 😀

Sorry, it is a K6-III+ (the mobile version).

I have the VIA 4in1 drivers installed, noticed the graphics card was running in AGP mode correctly as soon as I installed the Detonator driver for the TNT2 / GF2 MX400. The RAM is a matched pair of Crucial 100 SDRAM, but I will swap it out with some others just to eliminate that potential problem. I have some brand new TwinMos kicking around somewhere. The PSU I can change for another also, just to rule that out.

When I overclocked the K63+ I didn't change the voltage jumpers on the motherboard, so I presume it is still set to 2.0v. I read today somewhere that I should probably give it a little extra, somehwere around 2.2v. Someone said it improves stability at 500/550Mhz overclock and also that it eliminated their freezes in benchmarking. I will try this tomorrow. I read that higher voltage than 2.2v can bring your CPU to an early grave, so I'll just up it to 2.2v and see what happens.

FALLOUTBOY :

OK lots of things I need to look over, thanks for the information. I noticed that Windows 2000 did install the VIA drivers by itself, because everything was working AGP mode from the off. All i changed was the driver for the nVidia, and of course installed FastVoodoo unnoficial drivers for the V2 SLI. I'll grab the latency timer patch you suggested for Windows 2000, and see if that helps.

Some things to go on 🤣

Thanks for you help everyone.

I've had similar trouble with my SS7 builds, on a DFI and a FIC board with video cards made after 1999. Rage 128 and TNT2 work great but when I tried several GF2 variants and a Radeon 7500 it wasn't stable.

Read someplace that some AGP slots didn't deliver enough power but don't know if it was that or something about the VIA chipset. Wish I knew how to deliver power to a video through one of the molex connectors instead of the slow just to see what would happen.

One thing that has worked in some situations was to turn down the display acceleration one click in the system/display properties, this worked on a P2 system I had video problems with.