Knowledge gap. What board to use for adding Ram to A4000 ???

[Lemmink]

The ProgressivePeripherals for the A3000 is quite a collectors item. Besides it wouldn`t fit physically in an A4000 (unless you take out the doughteboard) the state of being a rare card will surely make it`s price go way over it`s actual worth (maybe even more then a 060er card would cost you).
Tha Fastlane is the same in terms of RAM-speed as the DKB3128. It`s the Zorrobus that is holding down the speed. But this is only natural; every board ever made, if it is an Amiga, PC or MAC has faster access to it`s RAM then to the ISA- ZORRO- PCI- NU-bus.

Of course the the Fastlane will go way cheaper then the DKB3128 but don`t expect any speedgains from it either.

[Lemmink]

Now that you keep hitting on the bus-problem, what's the use of an expensive Powerflyer IDE controller then if the bus speed slows a lot down

IDE on the amiga is way slower then the ZIII Bus of the A3/4000. Theoretically ZIII can achieve 25 MB/s, practically it is more down to 12-15 MB/s. For common IDE controllers in an Amiga 3.5 MB/s is a good rate while haveing nearly 100% CPU-Load. The Powerflyer (I assume it`t the same as the Fast ATA4000) can lift this rate by useing a higher PIO mode wich can transfer more data per CPU-cycle. While the CPU will still be near 100% usage you could get around 6-7 MB/s max.
You see when it comes to IDE the CPU is the bottleneck. With a decent SCSI-Controller like the SCSI-Module for the CS MKII or the Fastlane you can easyly get 7 MB/s in syncronus mode while haveing a CPU-load of only 20% max.
SCSI-controllers on ZII cards are in fact slowed down by the bus specification since ZII could only transfer 3.5 MB/s at best (never seen a HD go this fast on a ZII SCSI) but the CPU load is still low (as long as the card supports DMA)

[Lemmink]

If Zorro3 is backwards compatible with Zorro2, then why does Elbox design a Powerflyer (FastATAcontroller) for Zorro3 while there are other Zorro2 ide controllers on the market

Thats because ZorroII cards (16bit) can only handle 3.5 MB/s maximum. that won`t change if you stuck it into a ZorroIII Bus (32bit). If you want to go over those 3.5 MB/s you have to change the carddesign over to Zorro III. But ZorroIII design is more expensive then ZII, so you see it in the endprice.

I am also thinking about getting a fast ide controller but when I read your comments about pushing the cpu to 100% then it suddenly doesn't look so attractive anymore

The IDE protocoll is just plain dump (though it got a little smarten with increasing PIO Mode) it relies on the CPU to tell the controller where to put every byte from RAM to disk or the other way round.
SCSI on the other hand is a lot smarter,the CPU only tells the controller move those files fom A to B and tell me when it`s done (no pun intended ;-) ).
This is the reason why SCSI is allway a lot more expensive then IDE, it needs a lotmore logic especially on the drives itselve.
Since modern CPUs only shrug their shoulders at the extraload that is thrown at them from the IDE controller and IDE component are a lot cheaper SCSI practically vanished from the consumer market and is now mainly found on servers where still every CPU cycle counts especially when there are lots of drives to work.
For Amiga with it`s weak CPU SCSI is a must. The onyl reason for useing IDE on the Amiga would be that you don`t have the money (cables an terminators cost extra too)

Seems better to get a scsi controller and an ide-to-scsi adapter and hook up a 40 Gb ide harddisc to that...

This is definately a good investment as SCSI-drives usually cost twice as much as IDE-drives, especially when you want big ones. If you want to upgrade your HD you could allways recycle the adapter. I got two of them an never regreted it, low CPU-load and fast transferrates (though not as fast as as straigh SCSI-drive, but 7 MB/s easily).
You only have to see that the Adapter makes good contakt to the drive, I affixed mine with tape and folded papaer as a spacer.
When the Adapter breaks down you data won`t be lost, as you can then just hook it up to an IDE controller and go.

One last Warning, it isn`t all gold that is SCSI on the Amiga, there are some old SCSI controllers that don`t support DMA, so the CPU has to do the work again.
So if you want to get a SCSI-controler make sure it supports DMA, this is per se true for all P5 modells, single and on turboboards.