Update on the K7VTA bus problem

[Guest]

Has anyone ever had a problem with a motherboard not setting the bus speeds correctly? I recently ordered a Soyo SY-K7VTA motherboard and AMD Duron 700 processor along with a new case and hard drive. I originally configured with my existing memory, a 64mb pc100 dimm, and video, an STB Nitro 3D pci card with two 3Dfx Voodoo2's in SLI mode. The system would not boot until I reset the cmos using the motherboard jumper. When it did boot the first time, I set the bios setup to use the default setting for the cpu clock and to auto detect the memory clock. The system now would either hang on bootup or reset itself while trying to load Windows. Another cmos reset and bios memory set manually to 100MHz at CL3 got me into Windows. System was very unstable and would not allow loading of any programs without locking up completly. I next installed a Pny 128mb pc133 CL3 memory dimm. This allowed the system to bootup more reliably but it still crashed while loading games. I next tried an ATI RageIIc agp card. The system ran but the screen was covered in pink vertical line amomolies and still crashed. Next I installed a new Creative Annihilator2MX DDR agp card. I was able to load the games now but they all crashed, either on startup or within a couple of minutes. The games were MS Combat Simulator 1&2 and Heavy Metal FAKK2. The radio chatter and gun sounds in CFS2 dragged so as to not be understandable. I knew something was wrong but not in the way I had the system setup. I downloaded a copy of SiSoft's Sandra Professional system anylizer and discovered some interesting things. I verified that the latest version of Sandra was 100% compatible with the AMD Duron processor, the VIA KT133 chipset and the ICS pll ic chip used on the motherboard. Sandra reported that the front side bus was running 100MHz(correct) X a cpu clock of 7.0 = 700MHz(also correct). The memory clock was shown to be running at 150MHz when the bios was set to auto detect the dimm settings. If true, this would help explain why the system refused to bootup unless the memory clock was manually set to either 100MHz CL2 or 133MHz CL3 in the bios setup. The agp bus reported to be running at 100MHz. This could explain the screen anomolies with the ATI card. The pci bus was clock divided by 1/2 and running at 50MHz. Perhaps the pci based AC97 codec audio chip could not stand being overclocked and would explain the wierd sound in CFS2. The isa and dma buses showed similar increases being clock divided by 1/4 up to 13Mhz and 7MHz. I tried an experiment by setting the front side bus in the bios to the lowest setting, 90 fsb/30 pci. Sandra reported the change correctly on all the system buses. Front side bus was now 90MHz X 7.0 = 630MHz processor speed. Agp=90MHz; pci=45MHz; isa=11MHz. With the bus speeds set lower the system has allowed me to load and run all three games but it still crashes. I can easily tell that lowering the bus speeds has increased the stability of the system but never as stable as it needs and would be if the clock divider was operating correctly. My understanding of the support chips on a motherboard would lead me to believe that the clock generator is defective and is not dividing the front bus frequency by the 2/3 necessary to allow the agp bus to run at the specified 66MHz. If it did, I would assume the pci clock divide of 1/2 would cut the agp 66MHz in half and give the pci bus the specified 33MHz and the isa would clock divide the pci by 1/4 and reach the specified 8.3MHz. It all makes sense to me . But if you disagree with my logic and have any recommendations for fixes I would be glad to try them. I really like the Soyo board but have run out of ideas. By the way, I have already tried every combination of settings allowed in the bios and manually by the dipswitches on the motherboard. Also downloaded and installed the latest bios and VIA 4in1 drivers from SoyoUSA web site. What should I do? I've posted in web forums all over the net and e-mailed Soyo but no one has any answers. I've read at least four web reviews on the Soyo and it received high marks for stability. That's what makes this experience so disheartening. Can anyone tell me if I have a defective board? Or what I can use to verify the clock generator and bus speeds. Am I whipping a dead horse and just need to seed the board back for a replacement? Have never heard of a problem similar to what I think I'm seeing. Any help would be greatly appreciated!

 

[TazMo]

I think the horse might be dead. But a couple of thoughts since you've done so much already. Your logic seems sound except that the AGP is function of the PCI not the other way around. i.e. PCI is set by a divider of the FSB then the AGP is set with a multiplier of the PCI. Anyhow I'm not an E engineer, but it's possible that it's set in hardware and the board is screwed, but because so much stuff is in the BIOS softjumpers etc. it might be set with software. I know you did a BIOS flash, but maybe try another download or another site if possible. I'm not familiar with that particular board, but if it is a jumperfree design and also has dip switches to manually set speeds, make sure there is not a jumper on the board that you're missing to enable/disable the dip switches. On the board I just set up there was a jumper and the all the dip switches had to be set to off to use the soft FSB in the BIOS. You've probably done/checked these things, but I figured I'd post a reply.

Sometimes you gotta remember not to fight the obvious the MOBO is broke-replace it.

Good Luck.