[iBenDVSE]

I overclocked my DVSE to 500 MHz and it works great! I can't remember my life without it!

[iBenDVSE]

Don't worry I fixed it.

[Kozmik]

Huh?

[iBenDVSE]

I posted that reply in the wrong topic.
Sorry.

[Kozmik]

How do you cool the iMac? Did you mount a fan in there somehow?

I am curious about chipping my DV to 500Mhz. Running @ 400 it only reaches 35°C (95°F). Besides it's easier than going to 450 MHz which includes moving 3 resistors instead of 1. And, if you install one of those huge pentium fans, you could go even higher!

[Kozmik]

Only 95° F??? How do you get it so cool? My iMac DV SE runs at 120° F on the average!

[Ivan]

how do you overclock your iMac. I have a iMac DV and would like to know?

[Kozmik]

Go to http://www.bekkoame.ne.jp/~t-imai/imacde1.html and find a way to cool the thing!

[joe]

Originally posted by iBenDVSE:
I overclocked my DVSE to 500 MHz and it works great! I can't remember my life without it!

How about some benchmarks Timedemo for Quake3? MacBench? What about cpu temp? Mine seems to run at 116DegF after it warms up. Did you have to add fans or larger heat sink? I was going to hold off until after my iMacDV warranty was up. But if the Q3 frame rates improve.......joe

[Kozmik]

HOW DO YOU GET YOUR IMACS TO RUN SO COOL???????????

[Todd Madson]

My wife's stock iMac DV SE runs about 138-145 degrees at all times on a wooden desk. I'm told putting it on a stand allows for more airflow. I've sped up her level 2 cache to 200 mhz, we'll see how that goes. I haven't thought about clock chipping her machine actually since it's still in warranty.

[Ca$h68]

Man. You guys sure cant tell a troll..... sheesh. This guy hasnt been back since, and his original post made no sense. I'm guessing he's BSing.

Also, fans dont dictate how fast you can go. Your chip does.. you could mount a 333 in a windtunnel, and it still might only OC to 500 because the electricity would be jumping traces...

Ca$h

[Evinyatar]

Kozmik> The reason why your CPU is so hot might be because you have an aluminium processor chip. They tend to run hotter than the copper ones. My 333MHz runs at 82°F and is copper. Check wether your CPU is copper or aluminium with this application: http://forums.xlr8yourmac.com/softwa..._Checker21.sit

[Kozmik]

Well, seeing as how all iMac DV SEs (which I already stated that I own one) have CPU revision 3.0 (copper G3s), I'm assuming mine is copper. Another reason I am so sure is that GaugePro tells me that same thing.

[Todd Madson]

Interesting. Checked my wife's DV Se and the CPU revision is 2.2 and it's sitting around 132 degrees now. Gotta get a stand for that thing.

I knew it!
I have a copper one, and it runs at 95 F°

[Kozmik]

My copper chip usually runs at 123ºF. The copper wiring process was not originally created for cooling reasons (as is evidenced), but for higher clockspeeds and better pipelines on advanced chips such as the G3, G4, and AMD Athlon.

PPC Checker says my chip is revision 3.1, copper.

Also, how do you OC the L2 cache? I've heard about doing that, but how is it done?

[This message has been edited by Kozmik (edited 06-17-2000).]

[Stogieman]

Kosmic, not all DVSEs have copper chips. Mine has aluminum
I want to overclock mine to 500 Mhz. Would this be too much for my aluminum processor? I'm afraid it will over heat. My processor currently runs at an average of 131°. And my warranty is up yet. What would you guys do?

[Kozmik]

So my copper chip runs only 8 degrees cooler than your aluminum chip? As I said before, the copper wiring process was not designed for cooling reasons.

[Evinyatar]

They weren't designed to run coolor, but they just do. That's a fact.

My guess is: There is enough variation in each individual chip that you would be hard pressed to find, in real life, the theoretical (cooling) advantage/disadvantage of either aluminum or copper chip. It seems that one identically labeled chip may be more or less efficient than another. How else to explain why Ca$h's chip runs so hot, compared to other identical chips in identical iMacs?

[Kozmik]

Yes, and why does my copper chip run hotter than some aluminum chips? It is not a fact that copper chips run cooler than aluminum chips. It isn't. Also, how the hell do you speed up the L2 cache?

i just dip my iMac into a vat of liquid helium, it keeps everything nice and frosty

[Ca$h68]

Kozmik, you run a program called G3/G4 profiler form Powerlogix. You can set your L2 cache's speed a LOT higher. I have mine running at 222mhz (stock was 133) and it runs fine and dandy, and didnt increase my temp at all. Neat eh?

Ca$h

[iBenDVSE]

Hey, let's all overclock our L2 caches and motherboards and while we're at it let's do our RAM chips and hard disks as well.

P.S I overclocked my DVD drive to go at 24x

[Kozmik]

How fast can the L2 cache go with the comp remaining stable and cool?

[joe]

Originally posted by Kozmik:
How fast can the L2 cache go with the comp remaining stable and cool?

My iMacDV L2 is reliable to 200MHz using PowerLogix G3 cache software. I've tested it faster (around 225MHz iirc) but the computer will eventually lock up under Quake3. But it's been at 200MHz now for quite a while and no problems. Too bad it wasn't as easy to clock the cpu.......joe

FYI: The Temperature sensor is IN the G3 chip, so you won't see any temp increase when boosting the cache speed, that doesn't mean that you are not running your cache too hot. The reason digital chips "break" when overclocking at a certain freq. is that all synchronous circuits use the clock at a sort of heartbeat. Synchronous design requires that the propagation delay(the time it takes a signal to carry through logic or wiring) between two clocked elements must be a bit less than the clock period(with other constraints of course). Once the delay increases beyond the clock period for ANY given path in the logic, the system quits working properly and usually you get a freeze. Digital IC's (uProcessors + other chips) are constrained to meet the freq they were designed for, but often exceed the original constraints(slack). However, even if the chip could be maintaind at a constant temperature, there would be a limit to the max clock freq. because the logic and circuit traces have intrinsic delay. Heat simply increases the amount of delay that is already there(resistance of traces increases with heat). That is why at "borderline" frequencies, the unit appears to work, but as it warms up, the delay increases beyond the clock period and the unit then fails. As far as copper vs aluminum is concerned, the copper process was invented to combat a property whereby as transistor geometry shrunk, the wire delay was proportionally larger than the logic delay causing the timing to be more layout dependant. The copper has lower resistance so signals propagate faster through copper traces of equal size(cross-section). The reason for the variance in temps and max freqs is that CMOS technology, as advanced as it is, is subject to process variations. It's impossible to manufacture .35u transistors which are all absoulutely identical!! These process variations can cause one chip to be able to be run at 500MHZ while another might only work at 450Mhz. The actual speed screening is done while testing samples of parts which came from the same wafer at the desired speed.


And now you know the rest of the story....


-- MacDoogie
-- VLSI Design Engineer

[Kozmik]

I increased the cache speed to 200MHz with that PowerLogix program, and it works beautifully! There's a noticeable speed difference in some things I do, also. I have a question, though. When you restart, does the cache speed stay at 200MHz, or does it revert to the original 160 and you have to set it again? Such information would be helpful.

[Ca$h68]

Hit "APPLY ON RESTART".

The end.

Smartass Ca$h. ehehe.

[Todd Madson]

My G4/400 was sitting at 199 mhz and I boosted it to 265.7 mhz that way and it
runs for weeks at that speed without a
problem.

Of course, having two fans in the case
helps.

My wife's iMac DV SE seems to work fine with the 200 mhz cache setting. We bought her a stand last weekend and amazingly the thing runs about 15 degrees cooler.