View Full Version : overclock pentium 100?
can someone tell me how to overclock a pentium 100 outside BIOS if its possible? i cant change FSB in BIOS, i dont know my FSB and multiplier.
thanks.
Sir-Epix
10-07-01, 01:50 PM
Originally posted by Elmo
can someone tell me how to overclock a pentium 100 outside BIOS if its possible? i cant change FSB in BIOS, i dont know my FSB and multiplier.
thanks.
Take the case off. Look for dip switches. It should have a sticker on the case that tells you what On/Off dip switchs do what. Slowly overclocker your cpu that way and make sure it is stable. Also make sure that you have proper cooling so you don't overheat the system. I don't know how well P 100's overclock so be careful. Have fun.
there are probably 2 sets of jumpers on your mobo for that purpose.
One set for multplier and one set for front speed bus.
With 100mhz pentium that could be 2x50 or 1.5x66.
Some mobo's have text on the mobo itself that sez what jumper setups give what multiplier/fsb settings.
Others don't and then it's "cross your fingers and try some" :)
Write down the original settings first...
Write the results on a piece of paper perhaps...
And as how far it can go.. it differs
I have a P90 that barely does 100
But also a P75 that does 120 (60% oc :) )
Gabertooth
10-08-01, 05:02 PM
OC guys,
Your FSB is 33 and your multiplier is 3x.
-Gabertooth
thanks for the replies, so can u tell me what to change first that would definitely not kill it?
BigJohn
10-08-01, 09:07 PM
hey elmo does it have a fan on it?
Originally posted by Elmo
thanks for the replies, so can u tell me what to change first that would definitely not kill it?
Your level of knowledge.
Try not to take that as an insult (and I hope that doesn't come off as arrogant), everyone has to start at the bottom. I suggest you check your manual for info on which jumpers effect which settings. If you don't have a manual then go to the web site of the manufacturer of your motherboard and see if you can download a pdf version of the manual. If you aren't sure of who made your motherboard then hopefully someone else who reads this can give you a link to a site that will help you figure that out (I know such links exist but can't think of one off hand).
Once you have info on what your options are and what your current settings are post them and we'll all take a look.
Also I suggest reading the guides from the main page. I don't know if any actually apply to something as old as a p100 but a little knowledge can't hurt, unless it's allowed to stay little.
Let us know the specifics when you've got them. :)
BigJohn, theres a fan.
eobard, i found a diagram of the motherboard on the inside of the case on a sticker.
also on the sticker there is information about:
cache memory table
switch block (sw1e1)
l2 cache size
microprocessor speed
j5j1 jumper
memory table
which of those parts do u want me to go specific about?
Originally posted by Elmo
BigJohn, theres a fan.
eobard, i found a diagram of the motherboard on the inside of the case on a sticker.
also on the sticker there is information about:
cache memory table
switch block (sw1e1)
l2 cache size
microprocessor speed
j5j1 jumper
memory table
which of those parts do u want me to go specific about?
Gimmie what you've got on switch block (sw1e1), microprocessor speed and j5j1 jumper table.
Current settings on Switch block (SW1E1):
1 - off
2 - off
3 - off
4 - off
5 - off
6 - off
7 - off
8 - on
Microprocessor speed information on sticker:
SW 75mhz 90mhz 100mhz
7 OFF ON OFF
8 OFF OFF ON
J5J1 Jumper on sticker:
1,2 - Recovery boot enable
1,3 - Normal operation*
5,7 - OPEN - ISA bus speed 1/6 of CPU*
5,7 - CLOSED - ISA bus speed 1/8 of CPU
* Factory setting
diagram on J5J1 jumper table:
_______
|2|4|6|8|
|1|3|5|7|
-----------
Originally posted by Elmo
Current settings on Switch block (SW1E1):
1 - off
2 - off
3 - off
4 - off
5 - off
6 - off
7 - off
8 - on
Microprocessor speed information on sticker:
SW 75mhz 90mhz 100mhz
7 OFF ON OFF
8 OFF OFF ON
J5J1 Jumper on sticker:
1,2 - Recovery boot enable
1,3 - Normal operation*
5,7 - OPEN - ISA bus speed 1/6 of CPU*
5,7 - CLOSED - ISA bus speed 1/8 of CPU
* Factory setting
diagram on J5J1 jumper table:
_______
|2|4|6|8|
|1|3|5|7|
-----------
Here's what I read from the info:
The ISA bus has a choice of divide by 6 or divide by 8, that implys that at least two of the fsb choices you have are 50mhz and 66mhz. The ISA bus is meant to run at 8mhz so 8*6=48 and 8*8=64 but once you figure in fractional values that aren't stated and the fact that no one ever made a computer specifically to run at 48mhz or 64mhz you have 50mhz and 66mhz as the obvious choices. The fact that one of your cpu speed choices is 90mhz has me concluding that you also have the fsb choice of 60mhz because 60*1.5 multiple=90 and 60mhz was also a common option on p1 boards.
Now because the 100mhz option could be either 66mhz*1.5 or 50mhz*2 I don't have enough to guestimate wether switches 7&8 effect the fsb or the multiple. Either way if the only choices for fsb are 50mhz, 60mhz and 66mhz I'm pretty sure you've got a socket 5 board, not a socket 7, so I doubt that any of the other switches on the switchblock affect voltage. Correct me if I'm wrong people but socket 5 chips all used the same voltage so socket 5 boards never needed to be adjustable right? Assuming that's true (and I'm just playing amateur Sherlock Holmes here) then you're free to test the switches at your leisure to see what results you get without any risk of permanent damage. Like I said, assuming that's true. The only definite suggestion I have is if and when you start testing switches on your board you set your ISA bus to 1/8, that way if the adjustment doesn't hold you'll know it isn't because you've got the ISA bus set too high. Sorry but that's all I've got. Now, would someone who actually has an Intel cpu take over please? Thanks.
i can confirm that it is a socket 5
Actually I just had a brain flash. Since you know switches 7&8 on the switch block control the speed (wether by fsb or multiple) and since there are 2 binary switches with only 3 choices for those 2 binary switches listed I'd suggest you try the fourth, unlisted, choice. I'd like to know what happens if you set both 7&8 on, my guess is that the machine will boot to 120mhz. Try it if you want and let us know what happens.
thanks a lot for your help, but before i try it is it safe? i just wanna make sure it wont cause permanent damage. like what are the chances of it conking out?
It'll surprise the snot out of me if setting the 7th and 8th switches on will cook anything as long as the heatsink is on and the fan is working. I've set all of my 3 current systems to speed settings beyond what the chip could handle and haven't destroyed any of them, I just set them back to their previous setting and they run just like before I tried to overclock them too much. The only problem is if your voltage is too much and the 7th and 8th switch aren't for voltage based on your info.
when 7 and 8 are both on it says "301 Keyboard Error" at startup and stays there. The memory test goes slowly and then the keyboard stops responding. thats all.
Originally posted by Elmo
when 7 and 8 are both on it says "301 Keyboard Error" at startup and stays there. The memory test goes slowly and then the keyboard stops responding. thats all.
You know what the bad thing about friends is: lending. If I hadn't loaned my only computer repair manual out to a friend I'd be able to look up the specifics on a "301 Keyboard Error"! :( Unfortunately I did lend out my only repair manual so I can't tell you what to make of that error. When you put the system back to previous setting did it boot as normal?
yes, its back to normal now
At this point I suggest finding out exactly which make and model of motherboard you have and then go to the manufacturer's web site and look up their online manual (or download a copy). Scour every word printed on the board for names and write down everything that displays when the system first starts up. That should hopefully give you enough info to find the manufacturer.
i looked up 301 Keyboard Error on yahoo and all the sites had "Reconnect keyboard with computer turned off" as a solution. obviously that doesnt work for me. i even connected a different keyboard but it still said the same error message.
do you know what the other switches (1-6) do?
Originally posted by Elmo
do you know what the other switches (1-6) do?
No idea, I'm out of steam on this one. I do doubt you'll do permanent damage if you try changing the settings of them though. I'm leaving this to those with more Intel experience than me. Unfortunately no one seems to be stepping up to bat. I suggest you bump this thread a few times, hopefully that'll get someone elses attention.
Good Luck.
when 7 and 8 were both on , did u set the 5,7 - CLOSED - ISA bus speed 1/8 of CPU ?
i dont know about the jumper settings but i think the ISA bus was still on 1/6.
again, is it safe to change these settings (it wont damage anything)?
well 1/8 is slower than 1/6 so no problem :p
as eobard say u should get 120mhz, and isa at 1/8 u get right speed of the isa bus, so just set 7&8 on and 5,7 - CLOSED - ISA bus speed 1/8 of CPU .
maybe that is the problem when u were set 7&8 both on and if your isa were at 1/6 not 1/8 that make 10mhz isa bus, 2mhz above standart.
U won't damage it changing the speed of isa bus slower.
Hope we overclocked that baby :)
after removing the cards that were obstructing my view of the J5J1 jumper i saw that 5,7 was *already* closed even though this was not the indicated factory setting. should i try it with 5,7 open?
maybe it can't be overclocked :(
I don't know.
if it were pentium 75 :D it would be alot more easy.
lol
oh well, thanks for all the help anyway. I might be upgrading it soon anway. :)
Doesn't mean you should throw out the old setup though. Two machines will give you an excuse to experiment with learning about networking. :)
i'd like to make a correction: there is no cpu fan in my pentium 100.
chilidogg
10-30-01, 12:22 PM
well back when I still had a p100 I was able to get it to 133 by changing its bus multiplier from 3x to 4x keeping the stock cooling and staying at the default voltage so if you can figure out your jumper settings you can probably get it that fast or higher no prob
but why you'd want a o/c'd original pentium I'm still pondering...
right now the J5J1 jumper is set it to ISA bus 1/8 of CPU even though according to the sticker on the case the factory setting is 1/6. Right now jumper (5,7) is closed. Is it a good idea to open the jumper, try it with normal switch settings, then try setting switches 7 and 8 on? This would give me an ISA bus 1/6 of CPU. I havent tried this yet.
Well, lemme give what I can....
I'm assuming that switch 7 controlls the FSB, and switch 8 controlls the multiplier. My reasoning is this....
Off Off --------- 75 = 50 x 1.5
On Off --------- 90 = 60 x 1.5
Off On --------- 100 = 50 x 2
100 can actually be 50x2 OR 66.6x1.5 (like on my P-100). From my guess, you can see that it would be logical that 7 controlls FSB and 8 controlls multiplier. Therefore, I can see the highest your board going is 120Mhz (on, on = 60x2) My P-100 hits 133, so you should be fine. Of course, that's with a heat sink that looks like it could handle a K6-2....
As to the whole ISA bus thing, I'm lost.... Don't even want to try to understand it.... But I would suggest trying both 1/8 and 1/6 to see if it boots stable. 1/6 would be fastest.
The keyboard error is a little harder to figure out.... I normally only get keyboard errors if something is holding a key down. If you can get into your BIOS (at whatever speed), check to see if there is anything relating to the keyboard.
JigPu
markedmundb
11-01-01, 04:09 AM
My advice is set it back to standard, and try to find the mobo manual online the advice I always give about finding mobo info is the following (gonna save it off, so I can just cut & paste in the future):
"Next time you fire up the system, press the Pause Key (usualy next to Scr Lk) and write down the BIOS Code (usually bottom Left hand corner below "Press DEL (or whatever) to enter setup"
Once you have this code, go to Wim's bios page http://www.wimsbios.com and look down the list of BIOS codes there.
Chances are you'll find out the maker of your mobo , model no. etc. from the deciphered code.
Once you are armed with this info, go to google (or your search engine of choice) and type in what mobo maker, what model no. and the word Manual.
This should hope fully bring a list of places with mobo manuals. If you get nothing, then try Jumper settings in place of manual.
Good luck!"
BTW A second system is useful (I have a un-oc'able 486DX2 66) in case you kill your main system, you can get on-line without having to resort to public access terminals, or annoying mates by using their connection to ask "WTF?"
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