Power Macintosh / Performa 6100 Overclock @90mhz

[uniserver]

Basically I just replaced this 30mhz oscillator with one that was 45mhz

I tried other speeds as well. However 90mhz is running stable, With fan cooling.

Don't think I want to push her any more.

The UI is noticeably faster, not joking at all. Its worth it.

Anyone know of a good PPC benchmarking program for mac os8.1 ?

 

[uniserver]

Ok one thing, It's important, This additional heatsink I'v added here is needed.

This IC gets very hot with out some passive cooling. Added a heatsink and it now sits at a reasonable 110F

Smooth Sailing @ 90Mhz (let it run overnight)

 

[trag]

At 90MHz and above on the PPC601, Apple always provided a Peltier equipped heat sink. I'm not sure it's really an improvement. While you get a fixed thermal gradient between the top and the bottom of the Peltier, the extra energy (heat) that the Peltier adds means that the heat sink (top end) is at a higher temperature than it would have been without the Peltier.

So the question becomes whether the gradient created by the Peltier is more (cooler) than the increased temperature of the heat sink.

See the upper left hand item on this page.

http://www.shrevesystems.com/misc.html

On machines which used it (later PM8100, PM7200/90? and PM7200/120) there was a 12V supply header on the logic board near the CPU.

But if your heat sink is doing the job, the above is probably only of historical interest....

Now, time for some over-voltaging...

Apple used a Linear Technology LT1086 voltage regulator to supply power to the PPC601. The LT1086 is an adjustable VR. You change it by adjusting the ratio of two resistors. I used to know which two, but it's not hard to figure out once you find the LT1086 on the circuit board.

So, in theory, if you wish, you could try over-voltaging the CPU to see if you can squeeze any more performance out of it. You might need more heat dissipation though.

 

[uniserver]

those are pretty cool i bought 4

i mean it said cool my processor or cool my beer, sounds good to me

 

[uniserver]

The guy just refunded my money for those Beer Can coolers Its a shame I kinda wanted them… I have no idea why, maybe out of stock?

 

[trag]

The guy just refunded my money for those Beer Can coolers Its a shame I kinda wanted them… I have no idea why, maybe out of stock?

He didn't give you a reason? Oh well. Shreve was kind of dodgy even when they were actively in the used/refurbished Mac business. Still, I felt a tiny bit of secure happiness knowing that there was always a place I could get those heat sinks if I needed them... Sigh.

I have a couple of extras lying around here. PM me your address and I'll send them to you.

 

[ClassicHasClass]

Why not just stick a G3 card in it? The 601 isn't really a great chip for overclocking.

 

[beachycove]

Did Apple use the 601v in the 8100/110 and the 9150/120 etc. before switching to the 604 in the 9500—? Or were the early PowerMacs all pure 601 processors?

 

[trag]

Did Apple use the 601v in the 8100/110 and the 9150/120 etc. before switching to the 604 in the 9500—? Or were the early PowerMacs all pure 601 processors?

I think Apple used the 601v in their machines which were faster than 80MHz, but I'm not certain. Were the non-'v' versions rated to run any faster than 80 MHz?

All the NuBus PowerMacs were PPC601 based. Amongst the PCI PowerMacs only the various 7200s and the 7500/100 was PPC601 based, unless there was a Performa that used it. The Power Computing PowerCurve/120 (PCI machine) also used the PPC601(v) chip.

I'm pretty sure that the core power to the PPC601v is 3.3V vs. the 5V used in the original PPC601. If one probe the Linear Technology LT1086 near the CPU on such machines, the 80MHz and lower machines read 5V and the faster PPC601 machines read 3.3V. At least they have in my experience.

I'm not certain about the 7200/90 though.

 

[Bunsen]

uniserver - pelteirs are a pretty common part. You should be able to pick up something useful from a bunch of places. Working out mounting and power being the interesting part.

Though I reckon trag might be on the money here; try adding a small fan to blow air sideways through the heatsink before you get into peltier cooling.

Why not just stick a G3 card in it? The 601 isn't really a great chip for overclocking.

Sure, but by OCing the logicboard, which is what's happening here, a later-added G3 will also be OCed.

Now, time for some over-voltaging...

Huh. I always thought it was undervolting that let you crank some extra MHz, by reducing the heat load.

 

[uniserver]

Got them thanks Trag! These things are really neat.

 

[Bunsen]

Hey uniserver, are the serial ports still working? I heard that was a common problem with OCed Macs; the serial clock goes out of spec or something.

 

[uniserver]

i will check this!

 

[uniserver]

Ok plugged in the Serial (printer)

Connected to my powermac 7500

Copied over techtool

Ran all tests

Completed 100% successful!

This thing screams, to go from a 60mhz slug to a 90mhz performer.

I'm slightly impressed!

This one also has the 256k cache simm installed its keeping up with the 90mhz cpu!

Switched into Expert mode to run L1 and L2 CACHE tests.

Passed.

 

[Macdrone]

Now get the video card and be in awe cool land.

 

[Trash80toHP_Mini]

Found an old 'fritter thread . . .

Peltier Junction/Chip Chiller Info

. . . thought it might be interesting.

 

[Bunsen]

Copied over techtoolRan all tests

Completed 100% successful!

Okay, but what about a real-world test - using the serial ports for a Localtalk transfer, for example?

You also might want to consider my cooling tips over here

 

[uniserver]

Localtalk transfer

That was test # one, That is how I copied techtool over from my powermac 7500.

 

[uniserver]

Peltier Junction/Chip Chiller Info

Very good info, somehow my experience with Peltier chillers is fairly limited.

I remember working on a customers AMD machine(back in the day), if i remember it was a 500mhz Slot style and he was running it at 800 mhz with one of of these fancy Peltier coolers, he was kind of bragging about it, had a very large passive heat sink.

He had just turned it off, I was installing some more ram. By accident my hand pressed right against this 200 degree monster, and it literally seared the flesh on the back of my hand, it literally had grill marks on it, just like a steak.

I had never dealt with that kind of heat from a cpu before, but it was extra heat generated by the Peltier.

Good link, thanks.