8500 General Memory Related Question

[haemogoblin]

Hi guys

I'm still at it, working on the my old trusty 8500 and trying to sort out why it keeps locking up under load.

First the setup

Mac OS system 9.1

Sonnet G3 333Mhz Daughter card

176mb Ram

B4 32MB

A4 32MB

B3 8MB

A3 16MB

B2 8MB

A2 16MB

B1 32MB

A1 32MB

External L2 Cache: Not installed

8gb Seagate Ultra SCSI via adapter - SCSI ID = 2

CD Rom Drive Matshita CR-8005A - SCSI ID = 6

ATI Radeon 32mb PCI video card

Question #1

Can someone please explain to me the Dimm modules these machines use, at first I thought I was dealing with SDRAM like in my G3 B/W. But I'm not am I? Can the 8500 use 3.3v modules or does it have to be 5v?

Question #2

L2 cache, perhaps I removed this and never put it back in the machine after taking it apart. Can you still get these and how much of a difference does it make to performace?

Question #3 (last one i promise!)

Am I right in thinking memory should go from big to small? Starting with the largest modules in B4, A4 and the smallest in B1, A1?

A big thank you in advance for anyone who can help me on this

 

[MJ313]

Hey there,

I've battled some issues with my 8550 so I feel your pain. Do you have any other CPU card you can swap in to rule that out as the issue? It could be the card is overheating due to old thermal paste.

Other then locking up are there any other issues going on? I am also wondering about your power supply.

I had to deal with failing caps on my logic board and replaced them in my power supply as well. It's all sorted now, but these Power Macs are starting to have issues with caps as well it seems.

Cheers!

Edit. Sorry I didn't answer a single question you posed. :-/

 

[haemogoblin]

This power supply is now, well new in that I bought it off eBay before Christmas. It seems to be working fine. The lock ups only seem to happen when I'm copying data from the cd to the hdd.

Which is why I'm just about to take the lid off and fiddle with the cables and the ID numbering. See if it shakes anything up or not.

I still have my old psu. I just need help identifying the caps. Also how difficult is it to recap an 8500 motherboard, not sure it's something I'd like to do personally.

 

[haemogoblin]

Lid is off, first thing I noticed. CD-ROM has jumpers on 1,2 but no jumper under TERM POWER. Now if I remember my SCSI, the last drive should be terminated?

 

[johnklos]

Answer #1: The memory is old fashioned fast page memory, not SD memory, and it's all 5 volts. New 128 meg FPM DIMMs for the Power Mac 8500 and friends cost $7.50 USD apiece from OWC:

http://eshop.macsales.com/item/Other%20World%20Computing/5MD128MBG/

Answer #2: The L2 cache on the motherboard is irrelevant since most if not all G3 accelerators have their own L2 cache.

Answer #3: Memory doesn't necessarily need to go from big to small. However, make sure that the DIMM sizes in each pair are the same. If they're not, then memory won't be interleaved. Interleaving speeds things up around 10%.

If you think memory is the culprit, spend $15 and you'll have two new DIMMs which'll give you more memory than all your current DIMMs combined.

Bonus answer: Regarding the SCSI CD-ROM drive, jumpers on 1 and 2 are there to set the SCSI ID. Termination should only be enabled on the last device which is usually the internal boot SCSI drive.

 

[haemogoblin]

Hey buddy

Thank you for all of that! And thanks for the link!

If the Sonnet Encore I have installed does have onboard L2 cache (I'm unable to find out, I only have an extension installed and no actually software to look at the card) then surely it would show in the system profiler?

In fact this is what I have

http://www.welovemacs.com/ppcg3333512.html

 

[johnklos]

Yes, it certainly has L2, but you do need the Sonnet extension to enable it. But I don't remember whether the extension updates stuff to make the L2 show up in System Profiler. You can always run a benchmark, then disable L2, then run the benchmark again - any CPU benchmark that has to access memory will be slower without the L2.

 

[haemogoblin]

I found my sonnet installer software, turns out it DOES install software for checking the card. It's called metronome. Running the software, reports my card is running at 337mhz and I have 512kb of L2 cache. I guess this means the answer to the system profiler, is no, it does not show up the L2 cache on the card.