Spicy O’Clock in an SE/30?

[APPLCOLC]

Hi! I own an SE/30 and some expansion cards, as I’ve been wanting to push my Mac to its limits. I heard of some overclocking device called a “Spicy O’Clock” which overclocks 68040 processors far more than what was intended. I thought it was very interesting and I was curious as to if it could work inside an SE/30 with an 040 card?

 

[MrFahrenheit]

The Spicy is an adjustable oscillator. Theoretically someone could adapt a design for any place an oscillator is.

However, there are limits, usually to do with system bus, memory access, and video bus. If busses are tied together it makes overclocking far more difficult, and sometimes impossible or not practical.

 

[Byrd]

Not for the SE/30 - my basic understanding is that everything is tied too closely to the 16Mhz stock speed, increase this without timing fixes and it won't work.

 

[jessenator]

if it could work inside an SE/30 with an 040 card?

it might be possile to OC the 040 card, but …it depends. Having no experience, save a brief period of ownership, I haven't mucked about with 040 upgrades, vs native 040 Macs (like the Wombats).

I would have a look on the forum for the development thread of Bolle's 040 accelerator clones (I don't recall which one…), but I do recall he posted OC speeds and after a certain point the cache was inoperable with the overclock, so the gains were actually negligible: i.e. it was faster at the stock 33 or 40 (don't recall offhand) with the cache than at a higher clock without the cache.

That said, depending on the breed and year of your 040 card, you might be able to at least get it to 40Mhz. I definitely wouldn't attempt it until I had researched the limits of the card, and I'd definitely have a heatsink (if it doesn't already have on) and fan handy, especially if it's a D50D mask rev (mine didn't make it to 40, but it was rated 25)

 

[Bolle]

but I do recall he posted OC speeds and after a certain point the cache was inoperable with the overclock, so the gains were actually negligible

Can’t find that thread off hand but it basically came down to what you just said.
With cache activated the Carrera040 tops out at 40MHz, an original Turbo040 will go up to 46-47MHz and I got a modified (faster cache chips, L88M CPU and rerouting of some clock signals on the card itself) to work at 50MHz with the cache enabled. The floppy drive fails when running faster than 48MHz.
The Carrera will go up to 50MHz as well but only with the cache card removed.

 

[jessenator]

With cache activated the Carrera040 tops out at 40MHz, an original Turbo040 will go up to 46-47MHz and I got a modified (faster cache chips, L88M CPU and rerouting of some clock signals on the card itself) to work at 50MHz with the cache enabled. The floppy drive fails when running faster than 48MHz.
The Carrera will go up to 50MHz as well but only with the cache card removed.

And there it is

IMO @APPLCOLC , it would be neat to play around with the Spicy o'Clock, but then less cumbersome to simply use a fixed-cycle crystal once you found a speed you like, but that's just me: less of things having to be secured inside a compact. Again, that's just me, but it looks like you could theoretically do it. One of these days, when I have time, I'll actually hook up my Spicy o'Clock in the Quadra.

 

[APPLCOLC]

And there it is

IMO @APPLCOLC , it would be neat to play around with the Spicy o'Clock, but then less cumbersome to simply use a fixed-cycle crystal once you found a speed you like, but that's just me: less of things having to be secured inside a compact. Again, that's just me, but it looks like you could theoretically do it. One of these days, when I have time, I'll actually hook up my Spicy o'Clock in the Quadra.

I see. Thank you! I have no real reason to get one just yet, as my only macs are my Plus, SE, and SE/30 and I have no 040 card just yet, but it is quite a neat device.