First post, by athlon-power
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I've posted about this system before, but I've recently acquired a new interest in trying to get the best performance that I can out of it, albeit safely.
Specs:
PCChips M570 motherboard w/ SiS 5591 Chipset
AMD K6-2 266/AFR
32MB PC100 @PC66
S3 Trio3D AGP
PCI 10/100 D-Link Ethernet of some kind
trying to find a sound card
Here's the big deal: I can, and have, overclocked the K6-2 266 up to "333MHz," but the motherboard seems to want to report it at 337. Unsure about that. This was done by changing the multiplier from 4.0x to 5.0x, and going to 5.5x (reported as 375MHz) causes it to throw a Windows protection error. This was all at a 66MHz FSB.
This motherboard can go to a 75MHz and 83MHz FSB, but the issue is the rest of the system, and how it is not isolated from this whatsoever. The PCI bus runs at exactly half of the FSB speed, so even going to 75MHz will overclock the PCI bus, let alone going to 83. The AGP bus is even worse- it scales directly with the FSB, meaning that if your FSB is 83MHz, the AGP bus runs at 83MHz.
Theoretically, I could put a PCI display adapter in and not worry about the AGP bus, but at an 83MHz FSB, the PCI bus runs at 41MHz, a 125% overclock which I seriously doubt most PCI cards are going to like.
The ISA bus, which I will be using, can switch between the PCICLK/3 or PCICLK/4, or a solid 7.159MHz, which seems to be a quite low number compared to the default 8MHz. I am not going to go with 10MHz on the ISA bus (83MHz FSB with PCICLK/4), and I am very uncomfortable going with 9MHz (75MHz FSB with PCICLK/4). I have no idea what 7.159 would do, or if it would affect anything at all. If not, then the ISA bus is now isolated, but the PCI bus will be boosted to 37MHz when running at a 75MHz FSB, and 41 at the 83MHz FSB. The PCI bus to FSB ratio is as far as I can tell, locked. This is very frustrating for me because this limits me to the highest stock frequency on a K6-2 at 366MHz- which is effectively the same as me just switching the K6-2 266 multiplier up to 5.5x.
The motherboard glitches out and reports the 375MHz as I said earlier, and switching the voltage does nothing (I went all the way up from 2.2 to 2.4v, no difference), and a Windows protection error ensues. I want to reach 366 on this processor without having to buy a whole new one if I can. I am completely open to other options, I've thought about this for a couple of weeks, but there is most certainly something I have missed.
This motherboard is, however, running the lastest BIOS which was modified to allow for more support on K6-2's, K6-2+'s, K6-III's, and so on. Here's the link to the website I got it from:
http://web.inter.nl.net/hcc/J.Steunebrink/k6plus.htm
Everything still works great, so I'm assuming the thing works because it mentioned that it posts to the BIOS the modification date (2006), which it does on mine.
Where am I?