trying to oc an old old board

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berky

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I recently aquired my mom's old (what i thought to be) pentium 150. it turns out it's really an IBM 150. anyway, the mobo (from the manual) supports the cyrix/ibm procs up to 150mhz, while the pentiums it supports to 200. just as a small side project and for fun mostly, i wanted to OC this thing as far as i can. i've been looking over the manual and have been trying to think of how i could possibly get it to go higher. i was thinking of maybe setting the jumpers so it tries to read it as a pentium and set it at 200mhz, but i have never oc'ed a cpu using jumpers and i am unaware of any consequences of these actions. if anyone has any insight into what i can do, i'd greatly appreciate it. here is a link to the mobo's manual.


http://www.dfi.com/download/MANUAL/VPSMANUAL.PDF
 
I wouldn't recommend OC'ing that system cuz it may kill it. Since it's an old mobo, it probably doesn't have a function to lock down the AGP/PCI ratio (i didn't read the manual.) It could affect your HDD and therefore, your critical system data.
 
well, there is absolutely no critical system data on the comp. i'm just worried about killin the thing so it won't boot again.
 
for a possible 50mhz gain i dont think it is worth the risk if you need the system. 150 to 200 is a large jump in percentage speed but in practice the extra 50 mhz isnt going to let you place halo on the thing.
 
haha... halo probably would take up the entire hdd (1.5 gigs).

it's not a system i need. just one im' screwing around with. however, i want it to screw with and not as an oversized paperweight.

basically, i just wanted to oc it just to see if i could.
 
Then go for it and let us know what happens. I mean shit, worse case is you blow the CPU and get another one from FS/FT forum for 5 bucks.
 
heres what you do you take the chip off and put it on at a weird angle and hammer the chip on the board and watch the smoke roll its quite funny
 
I had a cyrix@ 133 Mhz which I think easily went to 180Mhz. At this speed though it would burn you when the heatsink was tounched. A very easy oc overall.

(I think the 150+ was 133Mhz?)
 
pedant said:
I had a cyrix@ 133 Mhz which I think easily went to 180Mhz. At this speed though it would burn you when the heatsink was tounched. A very easy oc overall.

(I think the 150+ was 133Mhz?)
Click to expand...


yeah, i think the 150+ is around the 133mhz mark. it's listed in the manual. mine is apparently the 200+ which is the 150mhz. at least that's what the jumpers are already set to.

do you or anyone know if there is a big risk involved in having the mobo think the proc is an intel ?? i think that's pretty much the only problem i can see because if that works fine, the 50 mhz overclock is no problem at all.
 
Yeah i woudl think there's a risk!
well, wait... so you can put either the IBM or an Intel into the same socket? well maybe there wouldn't be any risk... donno how old it is, but check for some physical identifying switch, like the floppies have to not be written to, that might feel if the CPU is intel or IBM... otherwise, just try your best at it, you dont need the system, eh?
 
If you fry the cpu, let me know. Ive got the same one sitting here doing nothing(the cyrix). Something like $5 shipped sounds fair.
 
wow, look at all the disinformation in this thread. people who probably have never oc'd these old guys telling people not to do it because its scary and dangerous, LOL

I had an old P150 that I was able to overclock to 166 or 180mhz. The jumpers allowed the use of not only different multipliers but different bus speeds. It was unlikely to "damage" anything by trying the different jumepr settings...either the CPU worked when you booted it or it didnot. No exploding components, no overstressed things melting down. In those days, you didnot really stress parts by overclocking, unless you did voltage mods.

IIRC, the mobo I had used either 30mhz, or 33mhz bus speeds, and I got the best performance out of using 33* 4 (166 mhz), instead of 30*6. (180mhz).
 
Monkey34 said:
If you fry the cpu, let me know. Ive got the same one sitting here doing nothing(the cyrix). Something like $5 shipped sounds fair.
Click to expand...

cool... i'll try it out tonight... see what happens
 
theres too many noobs with there fancy new shit, an older board doesnt need to lock any busses down, they usually compensate for it, i for a p75 running at 133 right now. and it boots into win2000 :cool: :D :cool:
 
Actually, your 150MHz IBM/Cyrix 6x86-P200+ used the Socket 7 receptacle that Pentium 1 processors used. Only in this case, that 150MHz 6x86-P200+ used an FSB speed of 75MHz - 75*2. (150MHz Intel Pentium 1's used 60*2.5, while 200MHz Intel Pentiums used 66*3). Unfortunately, most Socket 7 mobos lacked a PCI bus lock, so that the PCI slots on most Socket 7 mobos ran at a rather steaming 37.5MHz when the FSB was set at 75MHz.

Don't confuse the 6x86-P200+ with the slightly newer, MMX-enabled 6x86MX-PR200+. The latter processor ran at 166MHz with a 66MHz FSB (66*2.5).

EDIT - I've just seen that DFI manual that you've linked to. It uses the now-forgotten VLSI Lynx chipset, which ran its PCI bus at 32MHz when the processor FSB speed was set to 75MHz (that was a nonstandard FSB/PCI divider ratio). Intel's i430-series chipsets ran the PCI bus at a smoldering 37.5MHz on a 75MHz processor FSB (for a 2:1 FSB/PCI divider ratio - the only divider ratio that Intel's Socket 7 chipsets knew).

And since your VLSI-based DFI motherboard cannot be set to any higher FSB than 75MHz, you will have to change the multiplier in order to overclock your CPU (remember, Socket 7 processors theoretically had "unlocked" multipliers, but running at higher multipliers than stock were not guaranteed stable or even functional).
 
so eagle, do you think you could give me some guidance as to which jumpers change the multiplier? :)

the only way i thought i could get this thing to 200 mhz is (if you look on page 18-19 of the manual) to set jumper 1 to 1-3 and 4-6 and then set jumper 13 to all off (p19). is this basically what you're saying? thanks.
 
berky,

The jumper block JP1 controls the multiplier. With a 75MHz FSB, you can overclock that P200+ to 187.5MHz by putting jumpers on 3-5 and 4-6 (2.5x). And putting jumpers on 1-3 and 4-6 will overclock your P200+ to 225MHz. However, stability at either of those overclocked settings cannot be guaranteed.

The jumper block JP13 controls the FSB speed - and the PCI and ISA bus speeds are tied to the FSB speed (for a 75MHz FSB, the PCI clockspeed is 32MHz and the ISA clockspeed is 8MHz; for other FSB settings, the PCI clockspeed is one-half the FSB clockspeed and the ISA clockspeed is one-eighth the FSB clockspeed (one-fourth the PCI clockspeed)). Thus, leaving J13 empty sets the FSB speed to 66MHz.
 
thanks man, i'll have to check that stuff out tomorrow. i dont' have time to do it tonight. i'll let you all know how it goes.
 
ok, first i tried oc'ing to 66fsb x 3 = ~200mhz. it loaded the bios stuff and started to boot from the cd, but crapped out. i tried rebooting and nothing came to the screen.

i then tried the following: (not necessarily in this order)

66x2.5 = 165
75x2.5 = 187.5
75x3 = 225
60x3 = 180

and maybe a few more. i dont' remember. anyway, in each config, i could hear the noise from the hard drive, cdrom, and system speaker and it sounded just like it does when it boots normally, but no signal was sent to the screen. it may be my pci graphics card, i'm not sure.

whatever the problem, it doesn't work, so i'm stuck with 150. also, it's kind of weird, but i don't think the 2.5 multiplier works. i think when i did the 66x2.5 it registered as 133, and actually worked.

any suggestions? or does this seem like a lost cause?
 
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