Questions for those who have overclocked their Dreamcasts.

[Quzar]

I would like to try to get a fair list going of who has, what clock speed they run it at and wether or not they used any sort of modified cooling. Basically I'd like to see about doing this myself eventually and want to see how the numbers pan out.

So, if you have overclocked your dreamcast, please put the clockspeed you have reached (cpu, gpu or both), if applicable, what speed of a clock generator you used, and what other modifications you made in terms of cooling.

Thanks a bundle (I may or may not start a little list in this post of everyone depending on the responses I get).

[LyingWake]

You might wanna get in touch with fatheadpi. I think he's fairly experianced with overclocking and the benchmarks they ran at.

[Morphv2]

Uh, perhaps now would be a good time to mention this. What was know of as the CPU and GPU pins arent exactly that simple. The *CPU* actually controls the FSB, not just the CPU, so it overclocks everything. And the *GPU* pin isnt actually a GPU pin at all. Its only a pixel clock. And if you think I'm crazy, just talk to the people who disect Dreamcasts at dcdev.

As for me, my 300MHz Dreamcast is almost ready .

[Quzar]

Ok, for reference, I only want overclocks that have occured and what modifications were used to make them (if giving absolute clockrates is too hard).

I think I might cross-post this at DCPS to get better answers.

[Morphv2]

Oh, thats easy. Gimme about a month, and I shall have a post for the books.

[Disheveled DrFreeze]

300 mhz DC eh?
sounds good, you planning any voltmods? cooling mods?

[Morphv2]

Voltage mod is nearing reality. Just gotta test the voltage line we found. Cooling mod done, which required a seperate housing for the DC GD-Rom.

[fatheadpi]

Voltage mod is nearing reality. Just gotta test the voltage line we found. Cooling mod done, which required a seperate housing for the DC GD-Rom.

Nice!

Said it before, and I'll says it again:

Of the systems I've done (and from my knowledge of overclocking, which is probably no longer as great as Morph's), final clock speed should be 252Mhz and 276Mhz. I'm not really sure what exact frequency / multiplication factor is applied for the GFX pin, but we've raised the clock on that about 25%, causes V-Sync issues but on VGA seems to pick teh gameplay up a bit.

Without doing any voltage mods, I'd say around 280 is the max... if you can get more voltage in, who knows? I'm not really pioneering with the overclocking bit, I've just got a solid forumla down that I like. We've got the first DCPS OC model working well, hoping to list it after my vacation's over.

[ptr.exe]

Thanks to fatheadpi, got my DC to 252Mhz. Now hoping to get it high enough for Chrono Trigger to run smoothly - 75% during battles.

[fatheadpi]

Thanks to fatheadpi, got my DC to 252Mhz. Now hoping to get it high enough for Chrono Trigger to run smoothly - 75% during battles.

Glad you liked it, it should help... I did a 276/GFX and a Chrono Trigger test, seemed to move a good bit quicker than on a stock DC, need to get some framerate tests done.

[Quzar]

The best test for gpu overclocking would probably be (homebrew/emulator that is) PCSXDC.

[fatheadpi]

The best test for gpu overclocking would probably be (homebrew/emulator that is) PCSXDC.

How do you figure?

I haven't really decided on a benchmark test yet, just wondering why you felt this would be a good choice.

[Quzar]

Because, last time i looked it used the 3d hardware as opposed to simply using the pvr for little things. Another good choice might be genesis plus pvr 3 or 5 or maybe the bumpmapping demos.

[fatheadpi]

Because, last time i looked it used the 3d hardware as opposed to simply using the pvr for little things. Another good choice might be genesis plus pvr 3 or 5 or maybe the bumpmapping demos.

Thanks Quaze, I'll keep that in mind.

[ptr.exe]

Didnt want to start a new topic, so just thought i'd post here.

At first my DC was OC'd really simply, without a switch or any other stuff. So i decided to make it a bit more professional and put a switch so i could go back to stock speed. When stock speed is selected it works fine, but if 252Mhz is selected then it boots but acts as if the DC has lost the signal for a split second, it will freeze, sometimes instantly sometimes 30 secs in. The crystal oscillator worked fine before, but i desoldered it to attach longer wire to go to the switch, perhaps i burnt it out soldering? perhaps the wire is too long? (25cm).

Any help would be great.

[fatheadpi]

It might be signal degradation, you've got to keep your wires and paths as short as possible.

[ptr.exe]

Possibly, but the wire is short as possible at only 15cm now, before it worked fine even at 30cm, as the C/O was outside the DC. I've removed the switch now and it works better, but it cuts out before the menu if they're is no disc, if there is a disc it will work 50% of the time.

Perhaps removing that 100ohm resistor in the trace would help? obviously keep the resistor in line with the 33.3Mhz but remove it in line with the C/O. Does anyone think this may blow the DC? as i really cant lose this one.

Also fatheadpi, what voltage are your C/O meant to run off? ive got it wired to the 5V rail, perhaps the C/O needs 12V? or that may just blow it.

[fatheadpi]

They should run off the 5V line, that's always what I've run mine off of, and that's what all the pinouts I found from Seiko said to use.

[ptr.exe]

Okay, well thats not the problem then, but wtf is causing this? it worked fine before and now i really cant figure it out. It cant be the C/O as ive tried 2, perhaps its the DC? as this is a rev1 but wont clock to 276Mhz, so maybe it just doesnt like it?

[Morphv2]

And once again, that is not a GPU pin, that is actually just a pxel clock pin.