What the hell is this? How do you get 90mhz from a 486 motherboard?
3 x 30 MHz.
wrote:3 x 30 MHz.
I have yet to see a 486 motherboard with a 30mhz jumper setting. Why would anyone create a 30mhz setting when there is 33?
wrote:I have yet to see a 486 motherboard with a 30mhz jumper setting. Why would anyone create a 30mhz setting when there is 33?
I thought the same thing when I tried to install an AM486 DX4-90 on a standard motherboard (Chaintech 4UPB) and couldn't find the 30 MHz jumper. Finally I enabled the 33 MHz jumper but it didn't work at all. Never tried it again since.
wrote:wrote:I have yet to see a 486 motherboard with a 30mhz jumper setting. Why would anyone create a 30mhz setting when there is 33?
I thought the same thing when I tried to install an AM486 DX4-90 on a standard motherboard (Chaintech 4UPB) and couldn't find the 30 MHz jumper. Finally I enabled the 33 MHz jumper but it didn't work at all. Never tried it again since.
Did you try 25? I'm surprised 33 didn't work. It would only be a 10mhz overclock which should be easy for these chips.
I'm pretty sure the DX4/90 was an OEM-only deal. I remember there being such an option on some of the low end Dell and Compaq systems for a little while at the tail end of the 486 era, and I wanna say my old Magitronic system had a 30mhz bus setting as well.
It just amazes me that anyone would even bother to use a non-standard bus setting. It probably cost just as much for one of these as it did for a regular DX4-100. The only possible thing I could think of that might justify it is if AMD had amassed a bunch of defective DX4 chips that wouldn't run at 100 or 120mhz and this was how they got rid of them.
How about poor old Socket 7 and 50, 60, 75, 83 and 95 MHz? 😁 😁 They really went overboard there.
wrote:Did you try 25? I'm surprised 33 didn't work. It would only be a 10mhz overclock which should be easy for these chips.
No, I didn't. There was a hell of a lot of jumpers on that motherboard, and I had already run out of patience when I tried to run Doom and Duke Nukem 3D with an Intel DX2-66 and got less than 5 FPS at 320x200. I haven't touched it again for years, must be still collecting dust in the closet.
wrote:How about poor old Socket 7 and 50, 60, 75, 83 and 95 MHz? 😁 😁 They really went overboard there.
And theres also teh awesome 96.2Mhz FSB 🤣, and on some boards (including ASUS) 60 and 66mhz also had a turbo setting, raising FSB by 2 more Megaherz!!1
wrote:wrote:3 x 30 MHz.
I have yet to see a 486 motherboard with a 30mhz jumper setting. Why would anyone create a 30mhz setting when there is 33?
Same here, none of my boards support 30Mhz FSB, though the ASUS SP3 "might" be able to be clocked at around 30Mhz FSB??
And it's indeed some OEM part.
Actually, theres some very interesting OEM CPU's floating out there, like the SX-16 and the Athlon XP 3200+ with 333Mhz FSB instead of the usual 400Mhz FSB 😉
wrote:wrote:I have yet to see a 486 motherboard with a 30mhz jumper setting. Why would anyone create a 30mhz setting when there is 33?
I thought the same thing when I tried to install an AM486 DX4-90 on a standard motherboard (Chaintech 4UPB) and couldn't find the 30 MHz jumper. Finally I enabled the 33 MHz jumper but it didn't work at all. Never tried it again since.
Where did you find your chip? I heard there were many DX4-90 remarks out there. And it's funny the DX4-90 won't even take a 10% overclock. Would be cool if yours still functioned 😉
I wonder if you can do 60 x 1.5 with it.
Got it on eBay some years ago. I think it was auctioned together with some other stuff, but can't remember exactly what else it came with. I don't really know if it still works and don't feel like trying it again. Would give it away for free if anyone is interested.
wrote:I wonder if you can do 60 x 1.5 with it.
The CPU only has two multiplier settings, x2 and x3.
wrote:Got it on eBay some years ago. I think it was auctioned together with some other stuff, but can't remember exactly what else it came with. I don't really know if it still works and don't feel like trying it again. Would give it away for free if anyone is interested.
You should keep it 😉
And just for the record, I'm not 100% sure mine is the real deal also, though if a set of expert CPU guys laid their eyes on it and noone said anything, I guess it helps spotting if a CPU is a remark or not.
But I'd say, keep it! If only for the weird geeky value it has 😜
Intel also made a 90MHz 486 on 30MHz bus, though I am pretty sure theirs was only used in laptops.
"Will the highways on the internets become more few?" -Gee Dubya
V'Ger XT|Upgraded AT|Ultimate 386|Super VL/EISA 486|SMP VL/EISA Pentium
wrote:Intel also made a 90MHz 486 on 30MHz bus, though I am pretty sure theirs was only used in laptops.
No matter how long you've been into retro computing and no matter how much you already know...when you think you've seen it all theres always something appearing from the horizon that you had no idea existed L O L!
wrote:wrote:I wonder if you can do 60 x 1.5 with it.
The CPU only has two multiplier settings, x2 and x3.
I thought 486 multipliers were set by jumpers on the motherboard?
wrote:wrote:wrote:I wonder if you can do 60 x 1.5 with it.
The CPU only has two multiplier settings, x2 and x3.
I thought 486 multipliers were set by jumpers on the motherboard?
The instruction for multiplication (to the CPU) is made by the motherboard, but not the multiplication itself. Unfortunately, the native instruction is only 1 bit on 486 boards, on or off. The CPU has a PLL frequency multiplier built onboard which then does the multiplication based on the motherboard's 1 bit instruction.
Some CPU's ignore this instruction, like a 486DX-33 doesn't have a PLL and cannot multiply the FSB. A DX4 CPU will set its onboard PLL to 2x or 3x based on what the motherboard instructs. A DX5 CPU will set its onboard PLL to 3x or 4x, based on the motherboard's 1 bit instruction. Some fancier 486 CPUs like the Cyrix 5x86 have a 2 bit register for setting the PLL multiplier (1x, 2x, 3x, or 4x), but the motherboard is still 1 bit and can only distinguise two values. For the Cyrix 5x86, you need to use other software post boot to adjust for the full 1x-4x swing.
Plan your life wisely, you'll be dead before you know it.
swaaye wrote on 2011-05-26, 23:03:How about poor old Socket 7 and 50, 60, 75, 83 and 95 MHz? 😁 😁 They really went overboard there.
You mean
40mhz (pr90)
50mhz (75)
55mhz (pr133)
60mhz
62.5mhz (stupid Intel turbo speed no one used)
66mhz
68mhz (the other stupid turbo speed)
75mhz
80mhz (socket 4 & 5 early)
83mhz
90mhz (PCCHIPS fake pc100 only PR350 compliant board)
95mhz
96.2/97mhz (433/533mhz)
100mhz
83mhz screwing with PCI dividers and corrupting HDDs was especially fun
