First post, by enaiel
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VIAFSB is a little DOS utility I wrote for changing the FSB on the couple of VIA motherboards that I own. Why should only owners of 440BX motherboards have all the fun? Sure, 440BX motherboards are faster, more stable, and more cooler... but at least now I can change the FSB on my VIA motherboards in DOS just like they can! Anyway, I thought I'll share it in case it might be useful to someone else. It initially only supported the 2 PLL that I had, but have since added support for more. If you can find the datasheet for your PLL, I can try to add support for it.
CURRENT SUPPORTED
VIA Chipsets: VT82C596A, VT82C596B , VT82C686/A/B, VT8233, VT8233A, VT8235
PLL: ICS94211, ICS94215, ICS94241, ICS950908, ICS9148-37,CY28316, PLL205-03, W124, W156C, W83194BR-39B, W83195R-08
USAGE
VIAFSB pll_name [fsb_freq[/pci_freq]] [-u|--unsafe]
EXAMPLE
Get FSB: VIAFSB ICS94211
Set FSB: VIAFSB ICS94211 100
Set FSB/PCI: VIAFSB ICS94211 100.00/33.33
Set FSB/PCI in UNSAFE MODE: VIAFSB ICS94211 150.00/37.50 -u
DOWNLOADS
(Total downloads of previous versions: 14!)
PARAMETERS
-h|--help: Print the Help screen.
[pll_name]: Select the PLL to use. If not supported, will list all supported PLL.
[fsb_freq]: Select the FSB frequency to set. If not supported by PLL, will list all FSB frequencies supported by the selected PLL.
[pci_freq]: Select the PCI frequency for the selected FSB frequency. Will determine the PCI divider.
-u|--unsafe: Run in UNSAFE MODE and allow FSB frequency changes across all PCI dividers. Otherwise, tool will restrict FSB frequency changes to those within the current PCI divider.
FEATURES
- Allows change of FSB frequency without requiring a restart.
- Runs on a 386 or later x86 processor.
- Compatible with several VIA chipsets.
- Compatible with DOS, with or without EMM386.
- Compatible with Windows 95, 98 and ME.
- Requires CWSDPMI.exe or a compatible DPMI host.
- Can be run from a batch file, or even from autoexec.bat.
DISCLAIMER
WARNING: USE AT YOUR OWN RISK! This software should not be used for mission critical applications. Author is not responsible for any damage caused to your computer from using this software.
ALTERNATIVES
CPUFSB/SetFSB/SoftFSB for Windows.
RayeR's SMB for Intel chipsets for DOS.
CREDITS
Special thanks to Vogons member @EduBat for help decoding ICS94211 datasheet.
Special thanks to Vogons members @jheronimus, @Zeerex, @elcrys, @havli and @Falcosoft for help testing the program.
Built using DJGPP. You can get your own copy of DJGPP from https://www.delorie.com/djgpp/
SCREENSHOT
TESTED
Motherboard | Southbridge | PLL
--------------------------+--------------+--------------
MSI MS-6369 | VT82C686/A/B | ICS94211
QDI P6V694T/A10T | VT82C686/A/B | CY28316
QDI P6V694T/A10T | VT82C686/A/B | ICS94241
ABIT KT7A | VT82C686/A/B | PLL-205-03
Unbranded MVP4 | VT82C686/A/B | W156C
PCPartner AP133TAS3-T205C | VT82C686/A/B | ICS94211
WARNING: USE AT YOUR OWN RISK!
FAQ
Q. I do not know what PLL is on my motherboard. The util does not support my PLL. Can I use any PLL that has a similar name to mine?
A. You cannot use just any PLL, even if they are similarly named, because each PLL uses different bits to set the FSB. Also, you cannot google for this information as motherboard manufacturers use differnet PLL chips with different board revisions, sometimes with the same revision as well! If the util doesn't support your PLL, please provide me the datasheet for it, and I will try to add support for it. See this post for what the PLL on your motherboard looks like.
Q. Why does my computer crash when I use this utility to change the FSB?
A. Stability when changing FSB depends on your motherboard. If the selected FSB hangs the computer when changed from the BIOS, or using programs like CPUFSB/SetFSB/SoftFSB, it will also hang when changed using this program. Also, FSB that is latched by hardware jumpers are inherently more stable than those that are selected in the BIOS or set using this program, as the latches are not trying to change the FSB on a running CPU.
Q. How do I choose the right FSB frequencies when changing the FSB?
A. With these VIA chipsets, only FSB frequencies that are within the same PCI divider work. Going across PCI dividers crashes the computer, requiring a hard reset. To find the divider, divide the FSB frequency by the PCI frequency. Even within the same PCI divider, the edge values are less stable than center values. The only way to change the PCI divider is to change the boot FSB frequency using hardware jumpers or from the BIOS. Not all motherboards have these jumpers or this ability in their BIOS. VIAFSB will now by default restrict the FSB to only those within the current PCI divider. Use the new UNSAFE MODE to override this behavior.
Q. How do I check if the FSB has actually changed?
Q. I use ChkCPU to confirm FSB changes.
Q. How do I change the multiplier on my CPU?
Q. I use SetMul to change the multiplier on my VIA C3 CPU.