Purchased a 400mhz G3 ZIFF Upgrade CPU but after installation G3 Still reports 266Mhz

[ComputerCompulsive]

Hi there,
Well here I was all excited to install my new CPU thinking I'd open up system profiler to see a 400mhz G3 cpu upgrade listed. Yet when the system booted up and I went into the profiler all I saw was 266Mhz. So what am I missing?

Attached pictures from the sale where he clearly stated it was 400mhz and shows it in system profiler.

Edit: Kind of wondering now if he overclocked it for the screenshot since I now notice the cpu has a 300 on the label not 400 hmm or am I wrong? :/

Advise/Help appreciated.

Thanks!

 

[speakers]

Hi there,
Well here I was all excited to install my new CPU thinking I'd open up system profiler to see a 400mhz G3 cpu upgrade listed. Yet when the system booted up and I went into the profiler all I saw was 266Mhz. So what am I missing?

You need to change the clock divider ratio. Refer to https://lowendmac.com/1997/overclocking-beige-power-mac-g3/

You may be able to over-clock it beyond 400MHz.

 

[ComputerCompulsive]

You need to change the clock divider ratio. Refer to https://lowendmac.com/1997/overclocking-beige-power-mac-g3/

You may be able to over-clock it beyond 400MHz.

I was just wondering about that. Seems like the Sonnet cards didn't need to change any jumper settings but a apple ziff cpu does is that right; Am I correct that this is actually only a 300mhz processor based on the 300 denoted on the label?

 

[phipli]

Hey R5D4,

I have been messing about with similar stuff today and yesterday. I got a new to me Blue and White G3, the B&W and Beige machines are quite similar. Like has been mentioned the ZIF board doesn't carry over the processor speed, its set by the logic board jumpers (except for some cards like the Sonnet, which choose to ignore what they're being told to do for simplicity).

Set the jumpers correctly and your processor will run at whatever you pick within reason. 33MHz boost over labelled is basically guaranteed, 66MHz over is very common and 100MHz (400MHz in your case) is common enough. I rarely don't run my machines overclocked.

Can I ask - do you have a beige or a blue and white G3? If you let me know I'll show you how to set the jumpers to get the most out of your machine

Here is my new monster

 

[ComputerCompulsive]

Hey R5D4,

I have been messing about with similar stuff today and yesterday. I got a new to me Blue and White G3, the B&W and Beige machines are quite similar. Like has been mentioned the ZIF board doesn't carry over the processor speed, its set by the logic board jumpers (except for some cards like the Sonnet, which choose to ignore what they're being told to do for simplicity).

Set the jumpers correctly and your processor will run at whatever you pick within reason. 33MHz boost over labelled is basically guaranteed, 66MHz over is very common and 100MHz (400MHz in your case) is common enough. I rarely don't run my machines overclocked.

Can I ask - do you have a beige or a blue and white G3? If you let me know I'll show you how to set the jumpers to get the most out of your machine

Here is my new monster

View attachment 11921

Hi There,
I picked up a Beige G3 a while back that I've really been enjoying and that's the one I would like to add the new cpu too. Problem now is that it's been pointed out that the CPU I was sold is actually a 300mhz cpu so I'm speaking with the ebay seller who sold me the CPU asking for a refund (or at the very least a discount) since he sold the CPU advertised as a 400Mhz processor in the listing and not as a 300Mhz cpu that had been overclocked to 400Mhz.

The seller has a decent rating 100% with over 500 sales at a similar cost so hopefully he'll want to make things right.

Either way I'll be looking for another Ziff 400mhz (500mhz would be even better) so I can defiantly still use those jumper settings

 

[phipli]

Hi There,
I picked up a Beige G3 a while back that I've really been enjoying and that's the one I would like to add the new cpu too. Problem now is that it's been pointed out that the CPU I was sold is actually a 300mhz cpu so I'm speaking with the ebay seller who sold me the CPU asking for a refund (or at the very least a discount) since he sold the CPU advertised as a 400Mhz processor in the listing and not as a 300Mhz cpu that had been overclocked to 400Mhz.

The seller has a decent rating 100% with over 500 sales at a similar cost so hopefully he'll want to make things right.

Either way I'll be looking for another Ziff 400mhz (500mhz would be even better) so I can defiantly still use those jumper settings

Here are the jumper settings for two speeds for the card you have.

I've labelled pin 1 (which is marked on the board) and the front of the machine. You'll need to remove the tamper seal sticker (Oh no! The Warranty! That expired decades ago! ), then remove the block. Sometimes you can manage to dismantle the block and re-order the contacts, but usually its best to just use new, individual jumpers.

The jumpers you'll need are 2mm, not the normal 2.54mm ones. They're available cheap in bags of many from Amazon or eBay or wherever.

Are the diagrams clear? I thought it would be easier to show you specific setups that apply. I'd set it up as 400MHz and then run a benchmark (I usually use Norton's System Info with only "CPU" and "FPU" selected) a couple of times. If it is stable, you've got a CPU that does 400MHz happily.

If you have any issues, drop it back to 366MHz shown above.

Shout if you have any problems.

 

[phipli]

BTW, the jumpers are here :

 

[S. Pupp]

I don't know if other manufacturers did this, but Sonnet for a time was putting high temp cpu's in upgrades and overclocking them. Sonnet claimed reliability was the same, since the chip was a high-temperature chip and could tolerate an overclock at the lower temps of a Mac. Still, I think the overclock was a 50MHz overclock, not 100MHz.

 

[phipli]

I don't know if other manufacturers did this, but Sonnet for a time was putting high temp cpu's in upgrades and overclocking them. Sonnet claimed reliability was the same, since the chip was a high-temperature chip and could tolerate an overclock at the lower temps of a Mac. Still, I think the overclock was a 50MHz overclock, not 100MHz.

Its something that has been done by a fair few manufacturers over the years. DayStar Turbo 040 upgrades sometimes came with HRC processors, or even regular ones, clocked higher than the printed value. Apple themselves produced LC IIIs with 16MHz processors running at 25, and LC III+s with 25MHz processors running at 33MHz.

Other manufacturers painted or put stickers on top of the processors (in the days before heatsinks), which I'm almost certain the only reason you would do would be so that you could put a lower rated chip on your board in situations where you knew there was sufficient cooling etc.

 

[Patrick]

didn't they just bin the chips ?

tested them to see what MHhz they were stable at, and then sold them as that?

I think a lot of chips actually tested higher. so they just slap a slower speed on the label and sold it as that slower speed. even though it was stable at higher speeds.

So often times, the lower speed CPU's can run higher also. Why its often ok to overclock....

Point is, i don't think there was a separate process for the 300MHz vs the 400MHZ chip. they just sold the chips at what they tested good at...

 

[phipli]

didn't they just bin the chips ?

tested them to see what MHhz they were stable at, and then sold them as that?

I think a lot of chips actually tested higher. so they just slap a slower speed on the label and sold it as that slower speed. even though it was stable at higher speeds.

So often times, the lower speed CPU's can run higher also. Why its often ok to overclock....

Point is, i don't think there was a separate process for the 300MHz vs the 400MHZ chip. they just sold the chips at what they tested good at...

I believe they used to bin by batch and location on the wafer (quality varies between the middle and edge of a wafer?), and only test a limited subset. Combined with, as you mention, if the 25MHz part was significantly outselling the 33MHz part, there is a chance that they would ship higher grade parts to meet demand.

Another factor is that there is always an overhead. They can't have the chips be unreliable in service, so you would want to find the limit, and then grade them to a lower level. Additional to that again, is that I live in the UK, where the temperature rarely gets above 30 degrees C... I've sat in a 6 degree C room happily overclocking way further than I'd try in a more... normal temperature room, or in California in the summer. The chips have to work just about anywhere in the world, but most of the world isn't pushing the limits.

Its rare a chip wont take a 20% overclock with complete reliability, and I have an Acorn A3010 with a 12MHz rated CPU that will happily take a 100% overclock (to 24MHz), at which point the floppy controller (not the general processor functions) becomes less reliable. That would be equivalent to running a 300MHz G3 at 600MHz... I suspect that ARM chip was a tad bid over spec!

 

[ComputerCompulsive]

Here are the jumper settings for two speeds for the card you have.

View attachment 11922

I've labelled pin 1 (which is marked on the board) and the front of the machine. You'll need to remove the tamper seal sticker (Oh no! The Warranty! That expired decades ago! ), then remove the block. Sometimes you can manage to dismantle the block and re-order the contacts, but usually its best to just use new, individual jumpers.

The jumpers you'll need are 2mm, not the normal 2.54mm ones. They're available cheap in bags of many from Amazon or eBay or wherever.

Are the diagrams clear? I thought it would be easier to show you specific setups that apply. I'd set it up as 400MHz and then run a benchmark (I usually use Norton's System Info with only "CPU" and "FPU" selected) a couple of times. If it is stable, you've got a CPU that does 400MHz happily.

If you have any issues, drop it back to 366MHz shown above.

Shout if you have any problems.

Thanks for this, It will come in handy when I get the new CPU (just ordered another that is actually labelled 400mhz this time - and it was cheaper too).

>>BTW, the jumpers are here

LOL yes I know where they are thanks Too bad I have to void my warranty

 

[Patrick]

aside, when i got a Blue and white tower used.. like a decade or 2 ago...

i thought it was soo rad it was soo easy to overclock it. (just move jumpers)

 

[phipli]

Sadly my PSU gave up today. Sigh.

I'm having a lot of trouble with power supplies these days.

 

[ComputerCompulsive]

Here are the jumper settings for two speeds for the card you have.

View attachment 11922

I've labelled pin 1 (which is marked on the board) and the front of the machine. You'll need to remove the tamper seal sticker (Oh no! The Warranty! That expired decades ago! ), then remove the block. Sometimes you can manage to dismantle the block and re-order the contacts, but usually its best to just use new, individual jumpers.

The jumpers you'll need are 2mm, not the normal 2.54mm ones. They're available cheap in bags of many from Amazon or eBay or wherever.

Are the diagrams clear? I thought it would be easier to show you specific setups that apply. I'd set it up as 400MHz and then run a benchmark (I usually use Norton's System Info with only "CPU" and "FPU" selected) a couple of times. If it is stable, you've got a CPU that does 400MHz happily.

If you have any issues, drop it back to 366MHz shown above.

Shout if you have any problems.

Worked like a charm on my genuine 400Mhz processor! Thanks Very much!

 

[ComputerCompulsive]

Sadly my PSU gave up today. Sigh.

I'm having a lot of trouble with power supplies these days.

PSU in which? G3 B&W? Is there a guide for an ATX conversion? I've been thinking about doing that for a spare G3 desktop board I picked.

 

[Certificate of Excellence]

PSU in which? G3 B&W? Is there a guide for an ATX conversion? I've been thinking about doing that for a spare G3 desktop board I picked.

ATXG4

Recapping the PSU might be a worthwhile weekend venture as well if you know the cap values. @The House of Moth has instructions for a G5 Xserve psu recap from his website. I wonder if he has similar info for a B&W psu?

 

[phipli]

Worked like a charm on my genuine 400Mhz processor! Thanks Very much!

Good news

 

[phipli]

PSU in which? G3 B&W? Is there a guide for an ATX conversion? I've been thinking about doing that for a spare G3 desktop board I picked.

A B&W. Well, it wasn't the PSU. There seems to be some sort of loose connection in the machine somewhere and sometimes it refuses to power on. Or possibly the caps are marginal.

It seems to be more reliable with the door open. I'll have to investigate.

An ATX conversion for the beige isn't difficult. There is a jumper on the board that sorts the soft power polarity, then all you need is to ensure that the power supply provides the -5v that is often omitted on modern power supplies. At least, that is what I understand having looked at them before.

I've powered a beige from a modern ATX 20 pin connector. All I did was switch the jumper over. I didn't do anything about -5v, the result was that the internal speaker was distorting (only half the audio waveform being produced I guess), but sound worked fine using the sound out port and an external speaker.

A certain website says that you have to rewire the ATX... I'm not sure I agree. The "Power good" is an output from the power supply that the mac doesn't use. Its part of the ATX standard, so if the G3 board was designed to work with an ATX and has the jumper selection, it is perfectly compatible with, and happy to ignore the "Power Good" signal.

Lacking -5V though is an issue, because it is a modern problem due to modern power supplies just leaving it out because it isn't used any more.

 

[trag]

I went looking for where -5V is actually used some time ago, and couldn't find anywhere. It was not a deep search and I was focusing on X500 (7500/8500/9500) machines at the time. As far as I could tell, the ATX conversion articles at xlr8yourmac.com (have to use Wayback) don't list -5 as even being provided by the stock supply on those machines.

At the time the Beige was introduced it was mentioned that that jumper sets it for a stock ATX PS. I think the towers used a regular ATX and the desktop had the custom Apple PS?

Anyway, all oldish memories, so may not be very reliable, but I remain dubious that Macs actually need -5V.

The Mac II family doesn't use -5V. The Mac IIci/IIcx power supply is used on the C/Q650 and on the PM7100. So at least through the NuBus Power Macs no -5V is necessary.

Not sure if something changed with PCI.

Later edit, okay looked a bit more: Found this: https://web.archive.org/web/2012010.../MacinPC_ATX_case/pages/PC-MAC_PS_pinouts.htm

Here's a screen capture of the relevant bit:

They might have added -5V with the Beige, but it seems farfetched.