help overclocking aca620

[Amiga_Daver]

Hi i recently bought a aca620 @ 16 mhz and have noticed that many ppl overclock them to 25 mhz. I´m new to overclocking and was wondering if someone could give me some tips on how to do this and what i need in order to do it.

[danbeaver]

While I don't have an ACA 620/630, overclocking requires a hardware modification where the timing crystal is replaced with a faster one.  The CPU may tolerate a small amount of speed increase, but often fails within 10% or less of tolerance.  Replacing the CPU with a higher rated one may allow further over clocking, but the supporting chips may not.  You have to ask yourself one question, "Do you feel lucky?"  Or grasp a concept, "Simply put, a 6 ounce sparrow cannot carry a one pound coconut!"

[Amiga_Daver]

Okey thx for the tip
The aca620 is supposedly overclocking friendly to 25 mhz so thats why i want to try it.

[smf]

I wonder if i's really true that the ACA620 should be overclocked with another crystal.
The manual states that the clock divider should be decreased to 2 instead of 3 to overclock it to 25mhz. I don't own any ACA620 or know anything about it, i just wanted to keep the discussion alive until anyone who has overclocked their ACA620 cards can confirm

[Amiga_Daver]

yes smf i have read that too ! so that was why i started this tread as it is a easy fix that alot of ppl have done.

[Amiga_Daver]

so do anybody know how to decrease the clock divider to 2 ?

[Oldsmobile_Mike]

Also keeping the discussion alive, I googled "overclock ACA620" for the heck of it. First couple threads came up said it would need additional cooling, also check this out:

amigakit.leamancomputing.com/catalog/images/Inside_ACA620.pdf‎

I'm just amused because I've never seen a technical whitepaper for anything Amiga-related, lol. It does mention overclocking, doesn't say how to do it either though.

Edit - try this link:  http://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=6&cad=rja&uact=8&ved=0CF0QFjAF&url=http%3A%2F%2Famigakit.leamancomputing.com%2Fcatalog%2Fimages%2FInside_ACA620.pdf&ei=TrRfU7n6MsuzsQSx2IDYCA&usg=AFQjCNHDh19qOXVoNHscpcjDgMKmnMFsqA&sig2=BVvtikSxkKS1DEHp4FiHNQ&bvm=bv.65397613,d.cWc

[Amiga_Daver]

First of all thanks for the tip and trying to make the discussion stay alive
I thought i would say what i done so far as to find out how to over clock the aca620.

1. contacted the reseller on which page it stated (over clock friendly to 25mhz). he dint know, suggested i exchange the crystal (and that is a big no no.).
2. i have read pdf inside the aca620 which says that it is possibly by decreasing the clock divider to 2 but not recommended due to more heat and becoming more unstable (which is also due to overheating).
3. i have goggled many times and not finding any thing new that i didn't already know.
4. have written some dude that made a youtube vid of the aca620 in 25mhz mode (not gotten any response thus far).
5. have sendt a pm to a dude that sold a A600 with an clocked aca620 on amibay (not gotten any response either).

[danbeaver]

Look for a set (2 or3) tiny SMD appearing traces and either cut or solder one to achieve the new divider.  Google overclocking the CSPPC for an example.  You will need a guide to which one to mess with, or do trial and error.

[Amiga_Daver]

thanks for the tip danbeaver ! i gonna wait until someone can tell me exactly which smd to solder of before trying any soldering.

[danbeaver]

Wise decision.