I have an 8600/250 which I bought new with the standard (2) 16mb dimms in slots a4 and b4. In addition I had the vendor add a 64mb dimm which they put in slot b3 for a total of 96mb of memory. Fine, works great. Then some months later I buy another 64mb dimm (indentical to the one they sold me when I bought the computer) from the same vendor and install it myself. Upon start up any of the following may happen: 1) Mac starts up fine but will not recognize the additional memory. 2) Mac starts up with a dark screen on the monitor accompanied by a "breaking glass" sound and progresses no further. My first thought is this dimm is defective so I call the vendor and make sure it is the correct dimm (64bit 168 pin 5v 60ns) and they say no problem we'll exchange it for another. The new dimm comes and same problem. Then I think maybe they're selling me junk so I go to a local vendor and buy another 64mb dimm and install it. Different brand of memory, same problem. No amount of switching slots produces any other results (good or bad) and this includes moving the original dimms around, removing them pairing them up as we're supposed to or not pairing them up. I then was given a 32mb dimm by a member of my family and tried that out without any success. The fact remains: the three original dimms work fine, the three that I have subsequently aquired do not and neither slot locations nor combinations make a lick of difference.

Any thoughts?

http://www.info.apple.com/info.apple...ec.taf?RID=263

Says that the speed for your ram should be 70ns.

I have an 8600 that has been pumped with combinations of 8, 16, 32, 64 and 128 mb chips with no problems. It currently runs 512 mb and has never had a ram hiccup. Go figure.

Try getting slower ram.

Try the usual drill... zap the pram (control-option P R) and reset the cuda button on the logic board (near the ADB controler).

I'll get back to you with further help...

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Eliott Wolfe
Winnetka, Calif

I zapped the pram and also pulled the battery and let it sit for a few hours, then installed a brand new battery. No difference. I couldn't find a cuda button anywhere on the logic board. I'm not sure what it should look like but I've heard it described as a red reset button. Do 8600's have cuda buttons?

Yes, the 8600 has a cuda button. You have to find the ADB (cuda) IC on the logic board (trace the route from the ADB connector). The button is red, and it's close to the ADB IC.

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Eliott Wolfe
Winnetka, Calif

[zac4mac]

Wolfe, they aren't always red. The one in my 8500 is grey. It's a small button(surface mount switch) just above the processor card slot towards the back, on my 8500. Make sure and press the CUDA switch with the cord unplugged, hold for about 10 seconds.
My 8500 has DIMMs in all 8 slots for a total of 240 MB interleaved. A few months ago, I had problems with RAM and ultimately wound up cleaning all the motherboard connectors with alcohol and compressed air. Try the RAM in other macs and verify it. Make sure the DIMMs are fully seated.

I found the grey cuda button (hidden under the cooling fins of the processor) pressed and held for 10 seconds with the computer unplugged. Still no difference.

At this point it seems the logical thing to do is verify the integrity of my dimms in another machine. Sadly, everyone I know here in Seattle owns a PC.

The slots are clean and dusted, the dimms are fully seated. The dimms that do work will work fine no matter which slots I put them in (I've tried them all). The ones that don't work fail to work in any slot I put them in.

Now common sense would suggest that I have some bad memory, and perhaps that's the case. But if I do, then I've tried four different dimms from three different sources and they are all bad. What are the chances? O.K. so maybe I've done something to them (handled them improperly or something?) but I've handled the other dimms in this machine and others as well as the processor, video card, ect. without any problems.

Next possability: I've got the wrong dimms. But unless they are mislabelled (and mislabelled four different times) then I do have the right dimms for this machine. (168-pin, 5 volt, 60ns) By the way, Apple recommends a minimum speed of 70ns. Isn't 60ns a faster speed than 70ns?

[Riemert.NL]

Make sure the speeds are the same
if the already installed ones are 60 ns and the new ones are 70 ns that could be the problem. Try installing only the new ones

[zac4mac]

I don't think 8600 are all that finnicky about RAM, but all the "official" references say to use EDO, never mentioning FPM for that mac. I have all EDO in my 8500. There is also another parameter called "refresh rate" that is either 2k or 4k. That one screwed me once with an old 550. The RAM worked in my 476, but I got the chimes of death on the 550.

Well here's the latest:

I bought yet another 64mb dimm and it works fine. This particular dimm is (as all the others are) 5v 60ns FPM. It is supposedly new. The brand is HIT. I bought it on Ebay for $71.00. Now what am I missing here? This same type of dimm costs up to $300 from the big Mac outlets.

As to the suggestion of trying only the new (non working dimms) in my machine, I tried that. I put one of the 64mb dimms in the computer after reomoving all the original dimms. Same routine: chimes of death followed by dark screen.

Now I don't know the difference between EDO and FPM, could someone explain please? Nor do I know what the refresh rate is or more importantly, how to know what it is on any particular dimm. What other parameters are there?One of the dimms is labelled as "BUFF DIMM" Does this mean it's muscular?