Official DC Overclocking thread

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.
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Post by Zealous zerotype » Fri Dec 08, 2006 8:21 pm

Thought I'd give a heya to you rob, nice to see you on the fourms and sorry I did'nt realzie you were here earlier.
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Post by robivy64 » Sat Dec 09, 2006 1:14 am

Whoa Zerotype whats up man? haven't talked to you in a while.

Yeah I haven't been here for too long, I just stick around this thread in case anyone has any questions.
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Post by Morphv2 » Mon Dec 18, 2006 7:05 pm

robivy64 wrote:Morphv2, what revision of dreamcast do you have? I assume it isn't a version 2 if you are hitting 270 MHz.
I am actually using a Revision1. It's running with 8ns GPU/Sound RAM, and 10ns system RAM. The system RAM gets quite hot, so I put some super low-profile heatsinks on there. Just cheap ones.

And 300Mhz might not be impossible just yet. I have come into possession of a Revision 0 Dreamcast sporting 8ns memory for both the GPU/Sound AND the system memory. In laymans terms, you aren't overclocking until you pass it's design spec. 8ns = 125Mhz, so I'm not even really overclocking til I go over 250Mhz. So in all reality, 133Mhz (270) will probably be a piece of cake for it, and 150 (300) may happen after all.

Of course, that is all assuming that the memory speed is the limiting factor.
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Post by robivy64 » Thu Dec 21, 2006 11:19 am

Keep in mind that the CPU is rated for a maximum operating speed of 200 MHz. Although it will run higher, stability will begin to vary depending on it's threshold.
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Post by Morphv2 » Fri Dec 22, 2006 2:44 pm

True, but the SH4 was built upon the .25um process and was designed to run without even passive cooling. For reference, the .25um Pentium III 'katmai' hit 600Mhz. I realize they are different designs, but they both have pipelined superscalar FPU's, and I believe the SH4 also has the same number of gate lengths as the original Pentium Pro, which was capable of 233Mhz with on-chip L2 cache on a .35um process.

Therefore, 300Mhz shouldn't be too much trouble. It might just need more to eat.
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Post by miggi03 » Fri Dec 29, 2006 2:51 pm

Hi, there. I attempted this mod well, still am attempting it and to my horror i lifted the copper trace wire from the lifted pin of the ic305, the only hope i can think of rescuing it is this, the hole exactly opposite this will still work if attach the 240 singal here? or is the motherboard now useless? Thanks for any reply.

UPDATE= It worked, happy days. Was hoping this would improve sega smash pack but i guess that's just sheer bad coding. Thanks for the help.
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Post by Morphv2 » Sun Jan 14, 2007 12:10 pm

use periods plz :(
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Re: Official DC Overclocking thread

Post by centralsnare06 » Mon May 21, 2007 3:07 pm

BUMP!

I'd like to bring the overclocking discussion back into action, as i've recently ventured into this area of modification. :D

Right now i've got a switch on the side of my DC to go from 200mhz to 260mhz (doesnt boot, waiting for 40mhz oscillator to come in), and basicly i tripped and fliped it while it was on :o to my joy, the thing wasn't fried, but it just sort of reset. I wonder, since it just reset (looked just like it does when i push my software reset button), could it be considered safe to do this?
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Re: Official DC Overclocking thread

Post by miggi03 » Mon May 21, 2007 4:39 pm

I did the same but mine freezes it depends on the speed you flip it but imo I would highly suggest not doing it as there is nothing to gain from it anyway, that's a shame about not booting though cause I was gonna go for 260 next also.
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Re: Official DC Overclocking thread

Post by centralsnare06 » Mon May 21, 2007 5:34 pm

yes i was pretty dissapointed as well :?

thanks for the info :)

people have had success with overclocking VMUs yeah? 7.3mhz?
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Re: Official DC Overclocking thread

Post by FamilyGuy » Mon May 21, 2007 9:59 pm

A russian guy was seling OC'd vmu on ebay (and is still I think), taht were oc'd to 7.2 or 7.5 mhz to sync with his 240 mhz dc.

About switching the clock while the power is on ... It might be harmless, but it don't hurt not to do it ... take no chance thus I've never killed a DC this way.


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Re: Official DC Overclocking thread

Post by centralsnare06 » Mon May 21, 2007 10:16 pm

great, i've got a 7.3mhz crystal i could try once i get my my dreamcast working at 240mhz. i'll be sure to post my findings! :D

by the way, any idea how much that OC'd dreamcast sold for?
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Re: Official DC Overclocking thread

Post by fahlim003 » Sat Jun 02, 2007 1:52 pm

This might be a strange question, but does anyone have footage and or willing to upload footage of Sega Rally 2 running on an OC'ed DC? This alone is my reason to go through with the OC, but I'd want to be sure it removes some of the frame dropping and or the horrible fps in general.
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Re: Official DC Overclocking thread

Post by centralsnare06 » Mon Jun 11, 2007 12:47 pm

hey fahlim

sorry if its too late, lol, but when i get time tomarow i might do a little video of sega rally 2, provided i can get my hands on a copy. it runs pretty slow on the normal dc you say?
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Re: Official DC Overclocking thread

Post by fahlim003 » Sat Jun 16, 2007 12:08 am

centralsnare06 wrote:hey fahlim

sorry if its too late, lol, but when i get time tomarow i might do a little video of sega rally 2, provided i can get my hands on a copy. it runs pretty slow on the normal dc you say?
The framerate drops in plenty of spots. Just compare it to the PC version which runs lightning fast, aka normally. Snowy and Riveria have big differences and it's really disapointing since I prefer the Dreamcast version. If you can upload a decent amount of footage of those or perhaps even more tracks I'd really appreciate it.
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Re: Official DC Overclocking thread

Post by neoknux_009 » Sun Jun 17, 2007 5:30 am

yeah about the OC vmu...so what happens to the vmu if its not OCed and the DC is? Does the dc just not read the VMU anymore? Or does ir read but theres no visuals?
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Re: Official DC Overclocking thread

Post by kohan69 » Tue Jun 19, 2007 6:55 am

neoknux_009 wrote:yeah about the OC vmu...so what happens to the vmu if its not OCed and the DC is? Does the dc just not read the VMU anymore? Or does ir read but theres no visuals?
using the official vmu, induvidual saves or entire vmu may will eventually get corrupted, especially the ones that autosave

some users reported that some particular third party vmus did not get corrupted with an OCed DC
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Re: Official DC Overclocking thread

Post by Serious Sam » Thu Jun 28, 2007 1:20 pm

Ok, I basically get everything about this hack but there's ONE thing I don't understand. If I'm going to be using a 40MHz Quartz Crystal Resonator, there's two pins on there right? So one pin goes onto the mobo pin right? Where do you connnect the other pin to? Do you just bridge the gap in the 33MHz CPU clock pin with the QCR?
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Re: Official DC Overclocking thread

Post by Morphv2 » Mon Jul 16, 2007 1:14 pm

Actually, the crystal oscillators that are known to work with this mod are 4-pin, and here's what you need to know:

Pin 1 - 40Mhz clock signal
Pin 2 - 5v voltage in
Pin 3 - ground
pin 4 - 12v voltage in? (cant remember ^___^)
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Re: Official DC Overclocking thread

Post by Serious Sam » Thu Jul 19, 2007 9:13 pm

Wow. Is this really worth it? I mean I heard somewhere that the CPU and RAM timings go out of sync and may present performance issues. Would it be better just to overclock the GPU?
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