Problem running 2 x DKB3128 on A4000T

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Okay, I am on a bit of a RAM mission, just for kicks.
I have two DKB boards, each with 128mb, I have 16mb on the mobo and I have another 128mb on the Cyberstorm.
I should have 400mb RAM in total.

But...I can't get more than 372mb. As soon as I put the last 32mb SIMM on the DKB board, the total goes back down to 272mb.

I can put any of the two DKBs in any Zorro slot alone, and I can see the 128mb on that board. It's not the SIMMS and its not the boards. They have the same jumper settings.

So, what gives here?
I'm running OS3.9 and I took out the Kickflash and Picasso IV for testing.

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You know it, buddy. If all goes well my Miggy is going to have three DKB boards soon!

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Surely someone else has run two DKBs in one Miggy?

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Update:

Tried 3 DKB3128 boards, and the same thing happens (I can't have more than one of them fully loaded).

The curious thing is: I can have all three of them loaded with 96mb of RAM, and that RAM is recognised just fine.

So it looks like it is not an upper RAM limit on the Zorro bus, it is a problem with how 128mb RAM is recognised per 'slot'

Will do more testing, it is very strange.

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The answer is (at present) because I can.
However back in the days when I was raytracing with Cinema 4D I frequently ran out of memory (and I had 128 +16 +2).

So yep, the answer is raytracing with complex objects.

I have another update here:

I found that these DKBs behave a lot better if the PIV is in slot two and a fully populated DKB is in slot 1. I can then have a fully populated DKB in slot 3, and a 96mb DKB in slot 5.
That seems to be the combination to use for now.

Total fast ram is therefore 496mb on my Amiga.
I have to test this, though.
Still not allowed to have all boards fully populated but I guess I can live with that (although it would have been cool to have a classic Amiga with 530mb RAM.

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Not just a nerd, a super nerd!

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Sure, I'll get on it.

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Here is the PIV in slot one, and three DKBs all with 96mb RAM:



Here is the PIV in slot one, 1st DKB has 128mb and the other two have 96mb:



Here is the PIV in slot one, next two DKBs have 128mb and last one has 96mb. All of a sudden, you lose one DKB!



When I put the PIV in slot two, I can have two DKBs with 128mb:



But I can't have the last board fully loaded, because it disappears entirely, or in one case it turned into 48mb

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Ja, its weird, but that makes sense.

Kin-hell, removing the PIV makes no difference.

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That's definitely worth checking out, and I'll try it when the Miggy is all back together with the other drives in place.

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I've been busy putting the Miggy back together (it was completely stripped for testing. I'm almost done, have to solder some fan wires.)
Then this weekend I can make a few more checks, but at present the last SIMM slot of the last DKB must remain empty or I lose the whole board from the RAM pool.
I also got an ATX PSU for the Miggy and found an unwanted 36gb wide SCSI drive I want to try (if it works I'll ditch one of the standard SCSI ones, probably the 1gb)
Oh, and I also built proper retaining standoffs for the Cyberstorm, and replaced some mobo screws and LED panel screws. It is somewhat of a major MOT for the old girl.

 :-)

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I don't have photos of the standoffs, but there are photos of the 3 DKB boards and also the ATX to AT converter in the photo album.

http://www.amiga.org/gallery/index.php?u=2374

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Okay, I have trouble running my 3.1 partition (getting recoverable alerts), but I have put a 16mb SIMM on the last DKB card, running 3.9.



So I guess for now, that's the max I can have. It's also the most I've ever seen on a classic Amiga. If someone has more than 512mb, I want to know how he did it!