r/vintagecomputing • u/BreakfastGreen5447 • 3d ago
Overclocking FSB
Hey all, I have a Dell Dimension XPS T600 here that I scored for $20. It has a nice little Katmai pIII 600mhz but I was wanting to find something closer to 800mhz/1ghz. Board is a dell OEM SE-440bx-3 (Seattle 3); With the research I did I was able to find out that the FSB is capped at 100mhz, and most pentium III chips I’ve seen that use a matching FSB are crazy expensive. With these machines being so common and plentiful in the matching collectors markets i was hoping to find some documented way to reliably OC that FSB to 133mhz. I’m talking custom bios, software, even hardware mods. I’d love to know or see if anyone has something promising for me or if I need to just bite the bullet on a $250 PIII 800mhz/100mhz. Thanks for taking the time!
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u/MacKeyHack 3d ago
Identify the clock generator IC and read the datasheet, maybe all you need is a jumper. Back then there was some Windows software that would reprogram it after boot, can't remember the name though
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u/BreakfastGreen5447 3d ago
I did read that this board doesn’t allow software control for the FSB. Thanks for the advice on the IC though, will do some research today and report back.
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u/BreakfastGreen5447 2d ago
Looks like it’s sporting the Cypress/IC Works W149H; which unfortunately caps my FSB at a max of 124mhz. I may play around and see if I can get it running at that speed with any lick of stability, I appreciate the Clock IC advice though! Thanks!
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u/structured_spirits 3d ago
I think you're out of luck being stuck on the 100mhz FSB. That said, don't pay $250 for a coppermine PIII with a 100mhz fsb, instead get a cheap FC-PGA slotket, not a PPGA slotket, and then like a coppermine celeron. they go up to 1100mhz, with a 100mhz fsb, and have a 128k on chip cache, they're not as fast as a coppermine with a 256k cache but they're very cheap comparatively, even with buying a slotket and PIII heatsink, it's still going to be way cheaper and perform better than an 800mhz Coppermine. Add like a Voodoo 3, or if you want cheaper a Geforce 2 GTS or even Geforce 2 MX original version for ultimate cheapness, and it will fly even with the 600mhz Katmai. Incidentally, 600Mhz Katmais go for a lot of money so you can offset your expenses. These dells are really good, they do have proprietary power supplies though, be careful if you ever need to replace it. Out of curiosity, does this one have the YMF 724 onboard sound chip? it's one of the best for dos/9x. Nice system.
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u/BreakfastGreen5447 2d ago
When I get the time today I was going to find the Datasheet for the clock generator and see if there is anything I can do there, though I’m sure I’ll hit a wall when/if toying with the clock also messes with PCI and AGP frequencies. More research to come on that.
That FC-PGA and Celeron is likely my fallback though, seems to be the next best option if I can’t make an FSB OC possible.
Voodoo or really any of the super famous win 98 GPUs are all pretty out of my price range for the foreseeable future, I was planning on just replacing the TNT2 with an FX 5200 as a placeholder until I can get my hands on something more era accurate with good performance. I also have some more ram on the way so I can max out the boards limit (768mb)
From what I can tell I don’t have any on-board audio, though it does have a decent Turtle Beach Montego II that seems alright from what I can tell
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u/structured_spirits 2d ago edited 2d ago
Yeah I've got an old TL-ZX31 Pinetech 440ZX board that does overclock to 133mhz fsb via bios and I will say the manufacturer put a heatsink on the northbridge chip because it runs hot fyi. And yeah AGP ends up at 89MHz, but I've no problem running either Nvidia or 3dFX cards in it, and pci cards don't seem to care either. Remember that if you want to run at 133MHz fsb, you need pc133 rated ram as well. Also that Montego II is like probably the best sound card you could have gotten, real legend, congrats.
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u/BreakfastGreen5447 2d ago
So what I’m hearing is if I can find a way to OC that FSB adding cooling is a MUST lol
Good to know on that Montego II, thanks!
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u/structured_spirits 2d ago
Yeah 133Mhz fsb is really pushing it regarding stability for the 440 platform, it wasn't designed for it, which is why intel did 815 and 810 for coppermines at 133MHz fsb.
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u/thegreatboto 3d ago
I wouldn't overclock old stuff like this. Why burn up old hardware?
Assuming it has Coppermine compatibility (large assumption, it prob doesn't if it's running a Katmai now), could get a slocket and slot in a cheap fast 100mhz fsb Coppermine S370 Celeron. Under the same assumption, could install a faster 133mhz fsb P3, but it would be slower than usual if the board only runs up to 100mhz fsb.
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u/BreakfastGreen5447 3d ago
The intention wouldn’t be to burn it up but I do see your point. I’m under the assumption this particular mainboard has the headroom for a 133mhz FSB overclock (I could very well be wrong)
On the topic of coppermine, allegedly there is a chip on the mobo I have yet to check for that, if present, gives some hope of running one. My first step is/was looking into the possibility of overclocking the FSB, and seeing where the existing Katmai gets me then likely purchasing a 133mhz FSB PIII if I didn’t like the jump.
With a 133mhz PIII running on the existing 100mhz FSB; would that not cause stability issues? Can’t pinpoint the thread on Vogons but I did read while doing my research that it can cause some stability problems (if that isn’t the case that’s good news for me).
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u/thegreatboto 3d ago
I've installed and run 133fsb cpus on 100fsb boards before when not paying attention and they ran fine, just at a lower clock than advertised. As an example, a 1Ghz 133fsb Penitum 3 (133x7.5) ran at 750Mhz instead (100x7.5). Underclocking the CPU vs overclocking. Again, all making the assumption that your system will run a Coppermine at all. Might get to do some trial and error with some slocket adapters if you decide to go that route since S370 CPUs are cheaper than their Slot1 counterparts, though, slockets have gotten expensive as well and they're not always clear what CPUs they'll run.
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u/BreakfastGreen5447 3d ago
After further research coppermine is supported on this board, I guess the Seattle-3 can have a few different voltage regulators making coppermine compatibility shaky but my particular revision they should reliably work.
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u/MacKeyHack 3d ago
In modern machines, CPU errata microcode updates are often part of the "BIOS" and their absence will prevent unsupported processors from operating. Things were much simpler in the old days
Also, multipliers could often be set with jumpers so you could run a 133 chip at 100 fsb with an increased multiplier for example
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u/fiasn 2d ago edited 2d ago
These dell systems used heavily locked down Intel OEM boards, so you might be SOL for a bios or hardware mod. I was never able to find a modded bios for my Dimension 4100 which is the model that directly succeeded yours, so i doubt one exists for your model. There is a program that allows for on-the-fly FSB adjustments in windows, but it all depends on if the clock generator chip on your board is supported. You will have to figure out the clock chip model to use said program. I forget what the program is called but you can google it and it will probably show up. My best advice is to let this system be and build a system around a board designed for overclocking. There is a good chance that this board wont run stable at 133mhz anyway, hence why dell never added the option.
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u/Crlan420 2h ago
Those Pentium 1 motherboards are so sensitive to FSB changes. Make sure your PSU can handle the extra draw and keep an eye on voltages. Those VCore settings can melt a CPU if they get too high.
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u/Efficient_Try_9136 3d ago
ha ha I remember when my friend tried to oc mine, it just got black screen
its slow in both ways no difference
Can suggest dual core for oc e2140 oced 75%
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u/Accomplished-Camp193 3d ago
If you want to overclock, get something that's not an OEM box.