i bought a new heatsink/fan
for my cyrix pr233 m2 (core 166mhz - 83 x 2) because the one i was using was meant for a pr200+ (and not very good). but anyway, now I've managed to succesfully overclock the chip to a core of 187.5mhz, which is an increase of 21.5mhz, which is pretty cool, i have used a bus speed of 75, times by 2.5, and left the voltage the same as before. Windows runs fine, no problems there, and it runs for a long time. It doesn't get too hot either. Another thing that's really good about it is that the fan on the heatsink is really really quiet! It was £4.70 and is green, not that you can see it from the outside. (my old one is blue, and was really really noisy! - it's not now though because it's not being used, but it's still blue and still around.)
I did try setting it to 2.5 x 83 (core 207.5, an increase of 41.5mhz), but it would hang, and just do nothing, so i set the core voltage up from 2.9 to 3.2 and then it worked for a long time, but got very very hot, and started coming up with errors in programs.
I suppose I could have tried 3 x 66 (core 200, an increase of 34mhz, making it equivelent to a pr266 (i think!) whereas at core 187 i think it's equivelent to a pr250, perhaps, but i don't know they have never made speed in between pr233 and pr266), but I was not keen on lowering the bus speed, as i had already lowered the bus speed on the step before. so i think i will leave it as it is at the moment, and then maybe if i continue to have this success with it, i may try some different settings. the thing is, if i set it to get another 5mhz, but use a slower bus speed, then i will loose performance because of the lower bus speed, so in some circumstances it's not worth bothering with that extra 5mhz core speed.
anyway, windows 95 isn't stable at the best of times, so it's a bit dodgey doing this kind of stuff because you'll end up makeing windows 95 even less unstable! Well, I don't know really, it's kind of debatable, because Bob (my pr300m2 64mb sdram 4mb 3d/2d pci 3.5gb udma2 vx pro) at home, is (almost) very reliable, or was when it had a pr233m2 in (i don't know because i came back to university after i put the pr300 in), so i'm not too sure about Janet at the moment. You see, because I have a motherboard that has an on-board gfx chip that uses system memory and only has EDO ram in it, it could be because of this that it is slightly unstable. I think that if I had SDram in, and a real graphics card in, then i may have a more stable system. Also my Windows 95 installation could be a bit dodgey at the moment too, and my hard drive could be too slow as well, but i don't know.
anyway, i'll go now, i should stop thinking about getting better performance from computers, because it always involves spending money, and then after about 6 months you want more performance or more hard drive space or something, and it just keeps going on and on. i think though, that a good way to do it is to only upgrade when a chip that is 100mhz quicker than your present chip is the same price or less than your prsent chip in price. i.e if your present chip is a p200, and cost you £50, wait till a p300 costs £50 or less and then upgrade.
here's the formula, to decide when to buy a new chip
IF ( newchipmhz - oldchipmhz ) >= 100
AND newchipcost <= oldchipcost THEN buynewchip
ELSE don't buynewchip