PDQ RAM WTF

[ClassicHasClass]

A friendly warning to future PDQ owners and those who have not yet cracked their black beauties' cases. LowEndMac, EveryMac and WeLoveMacs (my usual supplier for older model Mac RAM) all list the PDQ Wallstreet G3s as having two, count 'em, two slots for RAM with a maximum capacity of 512MB. Indeed, Apple System Profiler reported that there was a single stick installed in the bottom slot, 64MB worth. Fine, I said, and ordered two 256MB sticks.

Well, foolish me for ordering without cracking the case. The sticks arrived today, I removed the keyboard and took off the heatsink to find ... the lower "slot" that had the 64MB of RAM is soldered to the board. Yes, that means there is only ONE slot, NOT two.

I'm trying to get my money back on the second, unnecessary stick.

So, PDQ owners, do you have one slot or two? I'm curious, because this is probably something that should be brought to the attention of the spec sites. Yes, this is an M4753 (266MHz, which can only be a WS PDQ).

 

[quinterro]

Mine has two slots. Currently one has a 256MB stick, and the other has a 128MB. It has a 300mhz processor board. Let me know if you need pictures of the part.

 

[Unknown_K]

I have 5 Wallstreets of both types and there are 2 RAM slots on all of them. You can get to 512MB using 2 x low density 16 chip 256MB SODIMM of 66 or 100Mhz (you need 100Mhz on the type 1 Wallstreets using 83Mhz BUS).

Do you have a picture of this weird soldered on RAM?

 

[ClassicHasClass]

It's just soldered RAM with a single SO-DIMM slot above it. Nothing particularly special except it shouldn't be there.

It occurred to me after posting that it could be a third-party card, but the processor+RAM board says Apple Computer. It's similar to the layout of the Crescendo/WS, with only one slot there as well ( http://www.sonnettech.com/product/crescendo_ws.html ).

Edit: and just to be even more mysterious, the manual (which it came with) says there is also only one RAM slot.

 

[ClassicHasClass]

Poked around some more, but can't find anything else out about it. Anyway, here's the pic.

http://www.floodgap.com/iv/1100

With the slot empty (as shown), a single "stick" is reported in ASP with 64MB.

 

[ClassicHasClass]

Never mind, I am an utter and ridiculous moron. If I had simply lifted the whole CPU card out ...

Still, very strange that the manual says nothing about it.

 

[Unknown_K]

Yea, I was going to say flip the CPU card over for the other slot! Those soldered on chips are cache I think.

 

[ClassicHasClass]

Yeah, they must be. I still can't figure out why the manual would imply there was only a single slot, though. I guess Apple didn't want people messing with it.

 

[LCGuy]

Thats because like the very first iMacs, Apple didn't want anyone apart from AASPs touching or even knowing about the bottom slot, end users were only allowed to upgrade RAM in the top slot.

 

[H3NRY]

Speaking of PDQ RAM, if you order the low profile 256K stick for the bottom slot from OWC, you will need 2 of them, because OWC sends an 8-chip module which works when paired with another 8-chipper, but doesn't mix with a low-density 16-chipper. At least that's what I found with my 292MHz PDQ.

 

[Unknown_K]

I was under the impression none of the 8 chip 256MB SODIMMs work, you need 16 chip.

 

[H3NRY]

Me too. I ordered one regular size 256K from OWC and one low profile for the lower slot. When it arrived, the low profile had 8 chips, and the pair didn't work. However each chip worked by itself and was recognized for a full 256K, so I exchanged the regular module for another low profile one, and it works! OWC must have something special in those Wallstreet 256K low profile sticks. I have some other 256K 8-chippers for a ThinkPad, and they don't work at all in Wally.