Took pics and made an OC diagram

Discuss modifications you have done or plan to do to your Dreamcast or any other hardware, or discuss devices you want to build. If your console does not work or is acting up, ask about fixing it in here.
Alexvrb
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Post by Alexvrb » Mon Dec 27, 2004 7:44 pm

mattthemodder wrote:if you change the frequency that goes into where the leg of "CPU Multiplier" goes you'll up it.
How does that increase the multiplier itself? I was asking if there was any way to change what multiplier it uses, because it is locked at 6. Preferably without ripping anything off the mainboard. But I guess not.
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Post by Matt » Mon Dec 27, 2004 8:01 pm

You increase the Mhz the multiplier will multipy by
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Post by Vchat20 » Mon Dec 27, 2004 11:01 pm

yeah. overclocking the DC and overclocking your PC are different. in PC overclocking, the mhz raiting stays the same but you increase the multiplier which in turn increases the end-result cpu speed.

in DC overclocking the multiplier is stuck as well as the system bus speed, but increasing the system bus is much easier than trying to increase the multiplier.
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Post by Pyrosurfer » Tue Dec 28, 2004 10:24 am

There might be a way to change the PLLs frequency output. That is what a PLL is made for.
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Post by bizzle » Tue Dec 28, 2004 10:52 am

Vchat20 wrote:yeah. overclocking the DC and overclocking your PC are different. in PC overclocking, the mhz raiting stays the same but you increase the multiplier which in turn increases the end-result cpu speed.
Um.. wtf? When you overclock your CPU on a PC the clock speed (MHz or GHz) increases. Most CPUs are multiplier locked, that's why most people increase the FSB (Front Side Bus).
Example: Athlon XP 2500+ = 11x multiplier X 166 MHz FSB = 1826 MHz. If you want to overclock it, you'll increase the FSB. If you increase the FSB to 180 Mhz, then the CPU is running at 1980 MHz, becuase 11x multipler X 180 = 1980.
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Post by Vchat20 » Tue Dec 28, 2004 4:14 pm

sorry. that was my understanding from the few overclockable pc's ive dealt with. this pc isnt that lucky :roll:
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Post by Alexvrb » Wed Dec 29, 2004 11:49 am

As has been said, you can do both on many PCs, but otherwise you're stuck with a locked multiplier and have to work with the bus. What I was asking (multiple times) was if there is a way to change the multiplier on the DC without removing and replacing components. The answer is now obviously no, but I was getting a bit sick of being told that you need to change the frequency that it multiplies by 6. No, really? That wasn't what I was asking. :roll: So forgive me if I seem a bit vexed. It's just that in the case of the DC, I'd rather be able to run at like 216/232Mhz and keep all the buses the same. That would be enough to give a good speed boost and help eliminate slowdown, without introducing sync issues.
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Post by silentthunder » Thu Feb 10, 2005 1:34 pm

The maximum the dreamcast can be overclocked to is 266.66 MHz. I have not attempted to overclock my DC, but I found this document that says the max multiplier is 8. ( 33.33 X 8 ). So theoretically the max is 266.66 MHz without any testing. You would need a 44.44 MHz oscillator ( 44.44 X 6 ) to make it almost 266.66 MHz. You would probably have to raise the voltage also somehow. The document says the max voltage for the SH-4 is 3.6 V (I/O) and 2.0 V internal. If oscillators are put in series, do they combine the MHz or is it divided? So you should be able to put oscillators in series or parallel to combine MHz. One or the other should work? http://mc.pp.se/dc/files/h14th002d2.pdf

I found this at http://mc.pp.se/dc/hw.html under Hitachi SuperH SH-4. There are two more documents.
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Post by Alexvrb » Thu Feb 10, 2005 9:42 pm

Those numbers are irrelevant unless you're building a new system based on whichever SH4 model that manual is referring to. You see, we're not touching the multiplier, we can't change it. We can only change the frequency that is multiplied by 6. So nothing holds us down to a set number like 266.66Mhz. There are limits, but they have nothing to do with that. Also that voltage "max" means little as well. My K7 CPU is specified for a given voltage, but that doesn't mean I can't overvolt the hell out of it if I so please, it is limited not by the CPU, but by whatever I feel like feeding it (until the board can no longer supply any more, or it burns out). The problem is finding a way to change the voltage fed to it in the first place. :(
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Post by kohan69 » Mon Apr 17, 2006 11:30 pm

http://nifty.amikai.com/amiweb/browser. ... c_id=nifty

^original guide partially translated, much more comprehensive than the English one. :evil:
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Here's a diagram I did to overclock my dc : tested =)

Post by FamilyGuy » Sat Aug 12, 2006 11:12 pm

Here is a diagram I did of what you should do to overclock your dreamcast to 240MHZ with a switch... Personnaly I did it but my buddy broked the lifted pin so my spare dc will now always be overclocked by he way I order another motherboard for 3$ so i'll OC it back :P

Here's the diagram:

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I Wish you'll like it !!
Last edited by FamilyGuy on Wed Aug 30, 2006 4:15 pm, edited 2 times in total.
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Post by semicolo » Sun Aug 13, 2006 7:41 am

Nice picture, isn't the switch on 240 Mhz position ?
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Post by FamilyGuy » Sun Aug 13, 2006 11:40 am

lol .. maybe yeah :P just don't really know how this switch work :P I mean ... the central pin is output .. 2 other pin are inputs.. but I dunno if to put the pin right will make the left or right input to be the one to be connect :P

By the way here's a picture of my own overcolcked dreamcast
It's overclocked at 240Mhz and it works fine.
There's not switch to go back to 200Mhz ... beacause :1-I don't have a switch right now... 2-This motherboard was broken ... because the 33.33Mhz signal wasn't working lol

Here's the picture:

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Hey Semicolo: c l'fun de voir un Qu?becois su un forum ... sa faisait longtemps jnava pas vu ...[/img]
Last edited by FamilyGuy on Wed Aug 30, 2006 4:27 pm, edited 3 times in total.
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Post by semicolo » Mon Aug 14, 2006 11:33 am

en fait je suis fran?ais d'origine, mais on ne va pas pinailler, je traine plutot sur le forum de dcreload.
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Post by FamilyGuy » Mon Aug 14, 2006 8:53 pm

Three-river = Qu?bec pour moi ... Donc .. ta beau venir d'ou tu veu ... tu est de ma province et pour cela : tu est Cool !! :D
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Who did it ??

Post by FamilyGuy » Mon Aug 14, 2006 8:55 pm

Hey I want to know ... who overcloked his DC ??

I did .. who else did in this forum ?? I saw the topics is somewhat old so ...
Just wondering ...
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Post by Lil' Jimmy » Tue Aug 15, 2006 10:55 am

I've just do this OC'ed dreamcast with FamilyGuy ...

Hi dude !!
Last edited by Lil' Jimmy on Tue Aug 15, 2006 12:37 pm, edited 1 time in total.
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Post by FamilyGuy » Tue Aug 15, 2006 12:35 pm

Lol .. humm ... Yeah .. lil jimmy is my buddy ... he helps me to overclock this DC lol so ...

His real name is M4c but .. who cares ??

lol

ps: Marco tu es con en criss :P

Hi dude!
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Post by FamilyGuy » Tue Aug 15, 2006 10:43 pm

I'm gonna try this one as soon as i'll get the parts ... ( switch and Xtal are hard to find in my location)

Wish me GoodLuck...

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EDIT: this didn't worked ... the 48Mhz signal seems too high .. will try lower .. the Scheme will work with any other Xtal value.
Last edited by FamilyGuy on Wed Aug 30, 2006 4:25 pm, edited 1 time in total.
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Post by Morphv2 » Wed Aug 16, 2006 5:59 pm

How many times do I have to tell you all, the 54Mhz signal is NOT the graphics clock! The graphics clock is simply drawn from the 33Mhz signal as well. The 54Mhz signal is for frame buffer.

I was told that by the person who designed the god damned "GPU".

I believe that makes the 3rd time I have said that
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