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Offline PulsatingQuasarTopic starter

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Overclocking Amiga 1200
« on: March 08, 2003, 02:24:04 PM »
Hello,

Couple of thoughts!!!

1) If I would the replace the 28 MHz chrystal on the Amiga motherboard with a 30 MHz or a 25 MHz one, what would happen???

Would the whole system go bonkers...  :crazy:  :crazy:

2) Many years ago in Amiga Format the technical letter answer guy said that you might get a faster system if the chrystal of the turbo board and the motherboard had one and the same timing.

If I would remove the chrystal of my turbo board ( 50 MHz) and put some elektronics behind it that divides it by two (25 MHz) and give that to the motherboard and the 50 MHz again to the turbo board, would that work!!!

The motherboard speed would then be exactly divided by two and the timing problem would be much better!!

Or is what the guy said nonsense!!

3) If I buy two graphic chip coolers and fans and glue them on my 68030 and FPU 50 MHz from the Blizzard-IV would it be able to run 60 MHz!!

If this would work I could run the board at 60 MHz and the 1200 at 30 MHz also having the same timing.


I'm I the only one with thoughts about an overclocked Amiga 1200???????
BlizzardPPC powered!!
AmigaOne-XE G3 800 MHz, 512 MB RAM, Radeon 8500, OS4
 

Offline PulsatingQuasarTopic starter

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Re: Overclocking Amiga 1200
« Reply #1 on: March 08, 2003, 02:25:35 PM »
Whoops... put it in the wrong place!!!
BlizzardPPC powered!!
AmigaOne-XE G3 800 MHz, 512 MB RAM, Radeon 8500, OS4
 

Offline Piru

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Re: Overclocking Amiga 1200
« Reply #2 on: March 08, 2003, 03:01:15 PM »
Quote

1) If I would the replace the 28 MHz chrystal on the Amiga motherboard with a 30 MHz or a 25 MHz one, what would happen???

Would the whole system go bonkers...

Yes.

Quote

2) Many years ago in Amiga Format the technical letter answer guy said that you might get a faster system if the chrystal of the turbo board and the motherboard had one and the same timing.

If I would remove the chrystal of my turbo board ( 50 MHz) and put some elektronics behind it that divides it by two (25 MHz) and give that to the motherboard and the 50 MHz again to the turbo board, would that work!!!

Most A1200 turbo boards have fast memory on board, that is on local bus, only custom chips and chipmem is accesses go thru the amiga bus.

You would not see much difference here, since the custom chip and chipmem access is much slower than the bus bandwidth anyway.

Dunno if "the sync" has any meaning here, maybe someone with better technical knowlege knows the answer. Anyway, even if it makes a difference, the difference would be only few percents, if even that.

Quote

3) If I buy two graphic chip coolers and fans and glue them on my 68030 and FPU 50 MHz from the Blizzard-IV would it be able to run 60 MHz!!


Probably. The FPU is more likely to give you troubles though, 68030 clocks to 60MHz easier.
Years ago, I ran my B1230-III 68030 at 60MHz (without any extra cooling) for some time before getting a BPPC.

Quote

I'm I the only one with thoughts about an overclocked Amiga 1200???????

Probably, because messing with the A1200 main clock is not a good idea. Overclocking accelerators works better, and lots of people have done that.
 

Offline voxel

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Re: Overclocking Amiga 1200
« Reply #3 on: March 08, 2003, 03:11:40 PM »
Answer to 1/ The 28.37516 MHz (Pal Amigas) or 28.63636 MHz (NTSC Amigas) oscillator MUST NOT be exchanged!

It's the main Oscillator from which ALL clocks are derived by AGNUS and all it's variants.

That's seems CPU & FPU (if present or the motherboard) clocks, extension slot clocks, VIDEO clocks and all custom chips clocks.

Changing it for something else than it's current values will result in DeSynched video and chips panic!

Answer to 2/ All modern turbo cards runs asynchroneously with the motherboard.
Thus NO.

Answer to 3/ Cooling the CPU & FPU will be a good idea, but before mounting a 60MHz oscillator in place of the 50 one on the blizzard, be sure that the chips are rated at 50MHz.

If yes your Blizzard will cope with it's extra MHz, you even can push it to 64MHz. But not behond because the Blizzard SCSI Kit IV will cease to work reliably or at all.

Needless to say that in this case you MUST cool your blizzard ;^)

BTW, DON'T TOUCH the motherboard oscillator!

Amigalement,

Jean-François.
Amigalement,
Jean-François Bachelet, Amiga nuts since 1985.
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Welcome to Happy Computing : Amiga! (© 2K4-2K8 voxel)
 

Offline PulsatingQuasarTopic starter

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Re: Overclocking Amiga 1200
« Reply #4 on: March 08, 2003, 04:14:18 PM »
Those are interresting answers!! Thanks to both of you.

Now I will have to get me some normally sized chip/graphic chip coolers and saw a hole in the Amiga 1200 case where the copro resides.
That doesn't matter; I have a spare case from towering my other Amiga 1200 with a BlizzardPPC and a BVisionPPC.

Now I will have to get a 60 MHz chrystal from somewhere in the Netherlands.
BlizzardPPC powered!!
AmigaOne-XE G3 800 MHz, 512 MB RAM, Radeon 8500, OS4
 

Offline mikeymike

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Re: Overclocking Amiga 1200
« Reply #5 on: March 08, 2003, 04:18:44 PM »
There doesn't seem much point in overclocking anything in my A1200, unless you could overclock AGA to do 800x600 in true colour @ 75Hz :-P
 

Offline BADHead

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Re: Overclocking Amiga 1200
« Reply #6 on: March 09, 2003, 11:48:17 AM »
when i changed my 030 for a 060 i was not too
overjoyed with the speed increase just that i now
use fast PC s oh well iam happy with it i just keep
my eye on the coldfire site V5 is 333mhz and then
start dreaming.  :-)
Crazy on a ship of fools  :whack: