Stock Heatpipe DC? Sweet!!! (Pics ~ 300k) Should I OC It?

fatheadpi · Post by **fatheadpi** » Wed Jan 19, 2005 5:28 am

I just won this DC off ebay last week for about 5 bucks. Tonight I was going to attempt an OC mod on it, so I tore it open. I swapped out the GD-Rom with my current personal DC that I chipped and fitted with a BBA a few days ago. I pull off the top metal plate to get to the mainboard, and what do I see a-staring back at me?

How cool is that? Now, are these heat pipes, aor is this a radiator? Also, would this be a better DC to overclock than a standard one? I was going to feed the 54Mhz clock feed into the 33 Mhz CPU feed, and this seems like the ideal DC to do it to. It's funny, but this was gonna be my scratch DC to figure out how to do some mods on. Now I think it'll be my personal ultra-DC... need to get another mod-chip.

I also has an idea for a cool LED mod. What if I grabbed a strand of XMAS lights, drilled some holes, and ran them around a DC case? I was thinking of doing this with one of those clear DC cases, seems like it'd be really cool!

riva16 · Post by **riva16** » Wed Jan 19, 2005 6:05 am

I'll give you $20 for the pipes! Or my truck! Actually if I remember correctly,t he pipes don't offer much more cooling than just the plain old fan does for some reason. You'd think as soon as heat i formed, the sink would pick it up and transfer it sown to the fan immediatly right? Not really. If there was water flowing through the pipes via a pump or osmething, then it would cool awsomely! Unforunatally, I don't think it does. Anyway, awsoem man. I'm stuck with just a fan...

Matt · Post by **Matt** » Wed Jan 19, 2005 8:47 am

They have some sort of gas in them that will flow towards the little tiny radiator thingy. Then when the gas is cold it'll go back from some more.

I don't think anyone has attempted overclocking a heatpipe cooled DC, go for it!

fatheadpi · Post by **fatheadpi** » Wed Jan 19, 2005 8:55 am

I've started overclocking my scratch DC, mixed results (as in it didn't work.)

I think I'm cutting off the clock to the GPU, but feeding it to the CPU. I say this because the unit boots up, spins up the GD-Rom, and loads a japanese game, although I get no "beep" after the access sequence. That should take a little CPU work, considering it's a chipped US system. My 1600 block bank indicator comes on, too. The only thing not working is the display; I get no display from any source (VGA or S-Video), and no audio either. I''ll eat breakfast and mess with it some more. For what it's worth, it's a rev. 1 board.

Disheveled DrFreeze · Post by **Disheveled DrFreeze** » Wed Jan 19, 2005 9:31 am

sweet system man, from the looks of it, it even has a temperatute sensor on the largest heatpipe

and as for the cooling, i havent opened my own dreamcast up that far, so i dont know how the normal cooling looks like, could anyone post a pic?

by the way, i was under the impression heatpipes work because the hot gases inside travel up to the cooling block, condensate while dissipating heat, and in liquid form, flow back to the heat source, but in the DC the heat pipes are placed horizontal, could that be hampering cooling?

Matt · Post by **Matt** » Wed Jan 19, 2005 10:41 am

by the way, i was under the impression heatpipes work because the hot gases inside travel up to the cooling block, condensate while dissipating heat, and in liquid form, flow back to the heat source, but in the DC the heat pipes are placed horizontal, could that be hampering cooling?

Think they still work the same. Yeah that does look like a temp sensor

Alexvrb · Post by **Alexvrb** » Wed Jan 19, 2005 10:59 am

The DCs with heatpipes don't cool that much better (although part of that may be later chips ran cooler, but not much... AFAIK die process did *not* shrink). The SH4 and PVR don't dump out that much heat to begin with, they're only using one heatpipe (each), and the heatpipes only connect to small metal fins with a small fan. Basically, the DC is very small, and they can't jam a whole lot in it without taking something out. You may have seen x86 heatsinks utilizing heatpipes. The good ones are often huge, and they often use many large heatpipes and a copper base, plus a much larger fan.

Basically heatpipes aren't automatically superior to solutions without them. They use them for specific purposes. For instance, solid metal only conducts heat over a distance so well. For short heatsinks, this isn't a problem, they conduct the heat very well - this is why you don't see heatpipes only going 1cm from the base to the top of a low profile heatsink.

But why don't PC makers just use bigger and taller heatsinks? After a short length, you start getting some seriously diminishing returns. It stops cooling better even though you're getting taller or wider, and you get other problems with an oversized heatsink.
So why are heatsinks with heatpipes so much taller and larger in many cases? Because where the top section of the heatsink would normally be too far away to conduct the heat, the heatpipes come into play. They pull most of the heat away from the base, directly into all of the fins above it, even the ones at the top. From there, the short distance left isn't too much for the metal to conduct heat and the air to pull it away.

Basically, heatpipes don't "cool better" on their own. They just help you move heat from one place to another, overcoming the conventional heat conducting limits of metals like aluminum or copper. If those were just metal rods and not heatpipes, almost no heat would reach the fan area to be pulled away.

For those curious as to why they stopped using heatpipes: They found a cheaper way to do it. The metal plates coming into contact with the chips, with the air flowing over them from the fan, proved to cool well enough. They didn't need to draw the heat to the fan with the heatpipes anymore. The fan would pull air over the hot metal, drawing the heat with it. If you want to seriously improve the cooling of your DC for overclocking purposes, there are lots of things you can do. But keep in mind that many of them will require more room, and perhaps a new case, depending on how far you're going.

fatheadpi · Post by **fatheadpi** » Wed Jan 19, 2005 1:16 pm

Having a wierd OC problem on my scratch DC. I lifted the 33mhz output off the board, bent it above the PLL IC, and soldered a lead onto it. Then I soldered a lead onto the board where the pin went, and another wire two pins over for the 54Mhz GPU clock. I can cross the 33Mhz pin and 33Mhz board leads, and the system boots up great. Disconnect them, and nothing happens. Cross the 54Mhz feed with the CPU clock input lead, and... nothing happens. WTF? The 54 Mhz GPU clock is the far-right pin on the PLL circuit toward the back side of the DC, correct?

Pyrosurfer · Post by **Pyrosurfer** » Wed Jan 19, 2005 2:16 pm

Your supposed to use a separate clock.

Matt · Post by **Matt** » Wed Jan 19, 2005 3:00 pm

It might be worth buying a clock generator kit if you want to play around with it a lot

Zealous zerotype · Post by **Zealous zerotype** » Wed Jan 19, 2005 3:10 pm

If it is what I think it is it can only go to 220mhz.

Morphv2 · Post by **Morphv2** » Wed Jan 19, 2005 3:19 pm

yeah, u arent supposed to use the GPU clock. Somebody already stated, cant remember who, that the DC wont work past 280mhz, and using the GPU clock of 54mhz would be pushing it to 324mhz. So i'd suggest get a seperate 40mhz crystal oscillator to push it to the "240" standard.

Btw, seperate note, what is that chip i see sort of nestled between the heatsinks and in front of the GPU? becasue I was recently sent a very odd motherboard that is HEAVILY modified off of that chip, and I have no idea what its for.

Matt · Post by **Matt** » Wed Jan 19, 2005 3:31 pm

I think you mean the BIOS

fatheadpi · Post by **fatheadpi** » Wed Jan 19, 2005 8:16 pm

Hmm, guess I'll have to find one, hope they're not too expensive. At least I have the leads in place. Can you overclock the GPU clock as well? I heard you can only do that if you're running VGA, which works fine for me and my KVM setup.

Pyrosurfer · Post by **Pyrosurfer** » Wed Jan 19, 2005 8:59 pm

http://www.jameco.com. This site is great, it has a large variety of digital/analog/general electrical supplies. You can get a 40 mhz oscillator there for very cheap, it's where I bought mine(although I haven't overclocked yet).

Yeah, you can overclock the video. Jameco doesn't have anything suitable for that though.

The japanese site said that heatpipe dc's get hotter than normal dc's. He tried heatpipe, then used normal after he found it was too hot.

Matt · Post by **Matt** » Thu Jan 20, 2005 3:35 am

The NES OC Mod I saw they bought a clock generator kit and slowly upped the Mhz to find something stable

fatheadpi · Post by **fatheadpi** » Thu Jan 20, 2005 9:47 am

I'll have to think about what I want to do.. i want ot use the heatpipe model as my final meagacast, I thought Rev 1 hardware was nice, Rev 0 hardware is f*cking durable! Should be easy enough to chip and OC, probably just run it up to 220 or 240. I'm looking at doing a modded clear case for it, probably try and open up the airflow.

fatheadpi · Post by **fatheadpi** » Thu Jan 20, 2005 10:15 am

So can I just run a lead off the big 5hz pin to an oscillator to power it?

Pyrosurfer · Post by **Pyrosurfer** » Thu Jan 20, 2005 2:19 pm

5hz? You mean 5V? Yes you can.

fatheadpi · Post by **fatheadpi** » Thu Jan 20, 2005 6:58 pm

Sweet! Gots to order me an oscillator and a switch!