Overclocking the DC and where to get the Increase

[ptr.exe]

I'll check amps probably tommorow.

funny thing is when you told me it was a 1.8V fed to the SH-4 i decided to waste some time and check the various ICs on the mobo for something matching/near that, and IC 104 was one of the ones i thought may be it, also a Sega chip with alot of pins next to the SH-4 makes 1.74V on a couple of the pins but that's probably nothing.

[Morph]

are you referring to IC501? If so, then thats the DC BIOS. And if that is indeed where the DC gets its 1.8v* from, then that still shouldnt be too hard to intercept. And it makes sense too, if it is coming from the BIOS chip, because that means the the voltage is BIOS controlled. But a few wires and a switch can change all of that.

Btw, is this it? (threw this together real quick in Paint)



If so, which pins? Fi you wanna tell me, you can just edit this pic and mark the ones red or something, so I know. You dont have to tell e the pin # etc.

And those revision numbers, I have no idea on their accuracy, since those are only the ones I have at my disposal (from my Rev: 0 board and one of my Rev: 1 boards) and could in fact vary by region etc.

[Cross]

Nah, the SH4 isnt underclocked that i can tell. The official SH4 product thingamajigger from Hitachi says its 200MHz. Odds are, either the DC version is a low power version (seeing how is hard coded low-endian) or perhaps it gets more juice to keep it more stable. I would doubt the assertion of more juice, since that would have increased the amount of heat, then again, that explains how the DC can hit a nearly 40% overclock without a voltage increase, something impossible on any other processor I have ever seen.

So, odds are, its probably the 1.99v lead, unless there is still another circuit on the DC motherboard that we don't know about. But I doubt that since I am almost certain that the 3.24v leads are for the I/O voltage. Btw, did you find how many amps or amp increments that thos pins run at? I don't wanna blow the circuit overloading on amps.

Nice finds there ptr!

My first thought as well with how well it pushes forward without a voltage increase 1.99 seems to be the most likely.

[quzar]

morph: He said IC 104 because he is talking about IC 104, it's a small chip (looks almost like a complex voltage regulator) on the back of the board almost directly under CE106.

On VA0 boards it is a Sharp 07VZ1H chip and on VA1 boards it's a Sharp 070XZ1H chip. If anyone cares, it is also a 070XZ1H on VA2.1 boards, but it has been moved to directly under the power supply pins.

I checked that on 2~3 motherboards a piece except the 2.1 (since i only have one).

[ptr.exe]

that's correct quzar, but in my post i started talking about another chip that generated 1.74V, thats what morph is talking about, also i think it looks like a voltage regulator because it is As for VA2 boards that doesnt matter as they dont OC well at all... just thought of something, maybe the reason they wont OC is because there isnt the massive excess of V that all the other revs have considering they have a differant chip in another place.
quzar could you check IC 104 on a rev 2 and post the V's, if the one on the others that has 1.99V is lower on the rev2's then its a good bet that that is the chip 'feeding' the SH-4 the vcore.

morph: No its not the bios, i know where that is, on the diagram you drew, go up to where the PVR2 is and above that theres a small chip that says 'Sega 315-6258', sorry when i said near the SH-4 i meant the PVR2. Probably isnt that. As for the bios, i thought it would be that so checked that first but found nothing near the 1.8.

tommorow i have a day off college, i'll check every pin again and post a pic showing all the points that are near the 1.8, their V and current. If i remember there are only about 5 excluding the IC 104.

However i really doubt its any of them, most likely the IC 104.

[Morph]

Ok, I know what chip you are talking about, IC401. Thats on the Rev: 1 board and I believe that might be the Dreamcast's ARM7 sound processor. On a Rev: 0 board it is marked 315-6145.

And if you would make that diagram ptr, I'd be much abliged. But you are probably correct about the 1.99v, since that would be most logical.

If we succeed in this, I will make a manual on how to go about all of this, and put it on my site. I'll submit it to Devcast if they'd like, and I can probably rewrite and polish up the old overclocking guide. Since this is a little more than overclocking the DC, I'm gonna affectionately dub what we are doing powerclocking (overclocking + power increase) .

[ptr.exe]

Yeah, 1.99 seems most likely, there doesnt seem much point in the diagram as majority of 'likely candidates' were quite below the 1.8V, such as 1.24V and 1.5V. I'll still check over tommorow and if i find anything new thats near 1.8 i'll post it, also i'll post the current as you asked previously. Just wondering; do you not have a multimeter? cant believe your doing this without one, they cost like £5.

Later on.

[Morph]

Ha, I couldnt possibly afford one at least until next Friday, as I am flat broke. Paycheck was WAY smaller than I had thought it would be. However I'll probably get one at the same time I get a 50MHz CO, which are actually sold nearby.

Once the OC is working, I'm gonna do some benchmarks vs a standard 200MHz DC and a standard OD'd 240MHz DC. I was thinking that, along with the Delicious Hardware Demo, I could also run Super Mario War, Quake 3 Arena, and Unreal Tournament all with FPS counter on and set on custom bot-matches to tax the hardware.

Sound good?

[ptr.exe]

Do you live in the UK? as i can not find any C/O over 25Mhz anywhere. Really annoying.

[Morph]

Nah, I'm based in Michigan. But that sucks. I just happen to live down the road from a privately owned electronics store who has stuff that you couldn't even hope to find at like Radio Shack or the like. A little more pricey, but, eh, never had no trouble with um.