I was getting so many mails on the issues of the PowerForce G3 card running in a 7500 (and similar systems) that
I felt a permanent page was in order. Here are the latest tips and feedback :
Railgun Runs 50MHz bus in 7500: Eugene Kuo wrote a mail describing his
surprise that his new Railgun runs 50MHz bus speeds in his 7500
(with no motherboard cache dimm). From his letter it appears his Railgun is a clone of the latest PowerJolt Mactell model that features 50+MHz bus speeds.
Interesting too that he did not need a fast cache dimm installed, as most 7500 owners reported report is required with most PowerForce design cards.
Update: Check SCSI Disk Termination!
Just a quick update to my previous comments (via your Card feedback page) on my Val4 7500 and
it's chronic instability after installing a PF 221/110 card.
I battled this beast for weeks, panicked that the dreaded Val4 problems would kill my 7500's future.
I finally decided with some help from PowerLogix tech "Jacob" that the problems were disk/SCSI related.
To cut a long story short my IBM-OEM 1GB drive shipped from Apple 3 years ago without bus-termination,
yes it IS the last device in the chain and I won't tell you what I wished on Cupertino's QA personnel that night.
I found the drive specs on an IBM site and enabled the "active termination" setting.
VOILA! a more stable Mac running the PF card at 300/150 than it has EVER been before. Hope this may help
some other poor schmuck.
" Hello Mike, [6/17/98 Update]
I have a follow-up report for your G3/7500 upgrade page.
My 7500/Powerlogix 220/512k runs great at 315mhz/45bus
with an old Techworks cache installed. This cache supposedly
only works in a 7200, but might be found for as little as $10.
(That was not the original story from Techwork's 'outrageous customer
The same cache never worked in the same 7500/same motherboard
running either the original 601/100 CPU or a Powertools 604/150
(from S900 UMAX). It used to crash, cough sputter, etc...
Other caches that never worked included the updated Viking 512k
and the Powerlogix 1mg (non-ultra). BLOL accepted the 1mg in return.
It is still true that if i remove the L2 cache, the G3 will
not boot, but the 604/150 will. The G3/No L2 cache freezes with a
gray screen prior to the HappyMac/flashing "?". Reinstall the Cache
and it works fine.
My machine was purchased 8/11/95, the first week 7500s were available.
after reading your report regarding the PowerForce G3 220/110, 512 kB
processor upgrade card, I immediately ordered it from BottomLine.
Today, 3 weeks later, I finally received my PowerForce card.
Now my PowerMac 7500 is really flying and the card runs rock solid @
Thank you very much for your recommendation,
Michael A. Byczkowski"
"Hey again Mike,
There _is_too_ an issue somewhere between the 7500 and the Powerlogix
I mailed you a few wks ago about my 7500. I searched around for a
replacement motherboard, and took it in. Today (thurs), I just got
mine back from the shop, again, a different shop even (ICNi in L.A.)
and they got my machine (with the old motherboard) to work with the
220/512k only if a L2 cache dimm is installed in the L2 slot.
go figure. This is the same machine that refuses to boot with a
L2 cache in the slot when running my old 604/150.
The Apple cache they used was P/N 820-0719-B. The engineer at ICNi
told me he even swapped the old board out, and installed the replacement
and it still refused to boot -- unless he put the cache in. The
The replacement board (which i didn't see) was to be P/N 661-1783.
I'm taking my machine home tonite, and will try my old Techworks
(for a 7200) cache. If it doesn't work, I'm gonna shoot it.
I really want to know what is with the TNT design, it's so infuriating.
Andrew Salamone sent some tips that may be of help to 7500 owners with APS PowerTools:
First of all, the 7200 graphics acceleration extension has got to go. As
soon as I stumbled upon that, all my LDS-inspired (remember Spock in
S.F.) video problems disappeared.
Also, the tech person (very kind and helpful, as well) at PowerLogix
said that the motherboard cache should definitely be removed if
possible. It's not possible. No matter what I tried, including removing
the battery for 20 minutes, the computer could just not get itself
together with out the cache. [many 7500 owners reported they needed a
good cache installed to run reliably -Mike]
The PowerLogix tech person also told me that the newer, shipping version
of the cache control panel can be a bit unstable. As Tad will tell you,
it was extremely unstable in my case, immediately trashing any connected
SCSI drive (and I do mean trashing) upon restart if the "enable on
restart" box was checked. She sent me the older version, and presto, it
worked the first time.
And importantly, don't wait until later to tell this to the unfortunate
few who use APS PowerTools: get rid of it! Reinitialize all drives with
something else (I used the Apple 8.1 (non HFS+)) BEFORE installing the
card. It may save them countless heartbeats as they otherwise watch
their drives be continually disemboweled by something in the PowerLogix
arsenal (most likely, the control panel). You gave me this advice, and
it was priceless. I wish that I had known this before my countless
clean-installs and re-inits.
So, as I said, I am now running the card at 301 with the Ensoniq Paris
card installed (for about 6 hours straight), and I have no symptoms
whatsoever, except that my system acts like it's on crack, blazing
through every task with unstoppable abandon. Thank you so much again for
all your help and patience (especially Tad). Mac Gurus are the Bomb!
And another report, amazing running at 341 Mhz!
Your note today regarding the known incompatibility with Powerforce g3 cards
and both the 7200 graphics accelerator extension and the catalyst based
motherboards is something that has been discussed and solved on the messages
board on your site (search for my name to read the messages). At least three
people have had the same problem, including me (with my PowerCenter 150).
The solution is to turn off the 7200 graphics accelerator extension and
leave in the motherboard cache. If the mother board cache is removed, the
start-up hard drive gets munged and if the extension is enabled, you have to
use virtual memory or there are serious video problems. I upgraded to an ATI
Xclaim 3D and left in my cache and am happily running my PF 275 at 341/227
(MacBench 1206/1087 with LibMoto). Since I couldn't remove my motherboard
cache without dire consequences, I installed NewerTech's MaxPower control
panel and extension and used it to disable the cache. That yielded about a
5-7% speed improvement and did not introduce and problems. I did corrupt my
hard drive 4 times before stumbling on the solution."
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