PCMCIA media card readers - suck 100% of CPU for copy?

Question

Hello!
I've bought two media readers - for camera memory cards - for my Powerbook. They are PCMCIA cards, one is a Sandisk card, for SDs, MMC, and Memory Sticks, among others. The other is a no-name brand for CF cards.
While the Powerbook (10.4.11, 2 GB ram, 1.67 Ghz) will recognize the readers - and the cards I insert - should I attempt to copy anything to or from the card, the entire computer gets thrashed. The CPU usage (Finder, Kernel_task, etc) go to 100%, and iStat Pro has shown CPU load numbers between 15 and 25! What the heck?
At the same time, if I insert either PCMCIA readers (with cards) into my old PowerBook 5300CS (OS 8.5, 48 MB Ram, 100 Mhz), the CPU is not fully used. Ditto for my 2.2 Ghz Macbook Pro and a Belkin Expresscard SDHC reader - in fact, it copies at the card's full speed and uses only a couple of % of CPU. It's running Leopard now, but it didn't have any trouble in Tiger either. That's why I think it's a Powerbook error.
It will happen with either reader, any brand/type of card, and has been occurring for quite a while - since sometime in early 2007. I don't remember it always acting this badly, so it may have been related to an OS update.
Does anyone have an idea of what the problem could be, and any fixes?
Thanks

Answer 1

Hi, N23. That's interesting. It was just a guess, as I said.
Since the beginning of 2004, when I bought my Titanium Powerbook as a new, recently-discontinued model, I've read everything in all the Tibook forums here at AD on a daily basis. Though my memory isn't what it once was, I can say with pretty good confidence that this problem of unreasonable CPU loading only when a CardBus card reader is in use has very rarely, and maybe never, been reported in those forums. This despite the fact that every time someone has posted there to complain that their camera won't transfer pictures to their Powerbook, I've recommended using a CardBus reader instead of connecting the camera. No one, to the best of my recollection, has ever posted back to upbraid me for giving that advice because it didn't work out for them. And this has included lots of people who were running Jaguar, Panther, and Tiger, and a handful who were running Leopard. So I agree with you that the problem is rare and weird.
I don't understand why this is, but I know from experience that some card readers (CardBus and USB; I have no experience with FW readers) can't properly handle cards with capacities higher than 1GB, which of course are much more common now than they were a while back. So I wonder whether a mismatched card and reader might be at the root of the problem for some people who have it. Unfortunately I don't recall exactly what sort of misbehavior occurred when I tried to read a 2GB card in incompatible readers. I know that whatever it was, I didn't check Activity Monitor at the time to see if it could shed any light on the problem. I don't have access now to my daughter's camera card or the readers in question to run any new tests.
I also wonder, without directly disputing your view that pre-Spotlight OS versions might have had the same problem, whether CPU-hogging Dashboard widgets could be implicated in some way. Widgets were often found to be consuming outrageous percentages of CPU cycles in the early days of Tiger. Might there be some widget most people don't have or use that swings into action when a CardBus reader is connected, but not when a FW or USB reader is? Sounds unlikely, but I have no idea. I'd be very interested to hear from anyone who can confirm that the CPU-overloading problem also occurs in Panther or Jaguar, and not just in Tiger and Leopard.