View Full Version : 512MB RAM is actually 256MB
Oct 9, 2003, 09:57 PM
I just bought 512MB RAM for my 17" AlBook which already had 512MB RAM and the chip is clearly marked 512MB but after booting the machine, About This Mac tells me I've only got 768MB. Apple System Profiler confirms this and shows:
Location Type Size
SODIMM0/J20STANDARD DDR SDRAM 512 MB
SODIMM1/J23REVERSED DDR SDRAM 256 MB
Any idea what could have happened?
Oct 9, 2003, 10:04 PM
Well, the ram is labled incorrectly. You are going to have to send the ram back and get a 512 stick.
Oct 9, 2003, 10:40 PM
What's that "Reversed" in there?
Are you sure you got the right kind of RAM? It might be a 512MB but for a different type of machine.
Oct 9, 2003, 10:43 PM
More likely it's bad RAM. Either way, send it back.
Oct 9, 2003, 11:40 PM
Doh! Thanks folks. I've contacted RamJet and I'll see what they say.
(I've no idea what the REVERSED means either).
some ram chips say their size either on the chips themselves and/or the pcb. So a ram stick might have 8 chips that all say (in very small type) "256m" or something like that. That would be a 256 megabyte stick. 256m is megabits, times 8 chips, devided by 8 bits per byte.
Oct 9, 2003, 11:51 PM
I'd be pissed...one of the first things I did when I got my PowerBook upon firing it up, I checked the system profiler to make sure I had the single DIMM 512 megs RAM and the 5400 RPM HD like I ordered BTO from Apple. Not that I think they'd screw it up, but I had a friend who got a custom Gateway and they put the wrong HD (40 gig instead of a 60 gig) and split the RAM instead of having it all in one slot. Things like that just make me worry a bit whenever I order something online until I can finally check.
Oct 10, 2003, 12:02 AM
I did look on the chip and it had a sticker that clearly showed 512Mb. Plus the order form was definitely for 512Mb. So it looks like a 256Mb chip was mislabelled.
Oct 10, 2003, 12:07 AM
I installed new 512MB chips in about 40 computers over the summer. One of them registered as being only a 256MB chip. If you'll notice, a 256 has data chips on one side of the chip whereas the %!@MB has data chips on both sides. When a 512MB chip registers as only 256MB this means that it has a defective bridge and that the back side does not register. You'll have to send it back for a replacement. Due to the sensitive nature of RAM chips about 2% are faulty. You'll likely have to pay shipping charges, but they should give you a new chip for free.
Oct 10, 2003, 02:14 AM
Originally posted by stoid
the %!@MB has data chips on both sides
Next time, don't try to type numbers in capitals :)
Oct 10, 2003, 02:42 AM
that's all I can say
Well, I can also say that I need to lay off the caffiene (SP?) and just sleep more
Actually it's a secret code, and in time it will reveal my plan to take over the world and destroy Microsoft totally and entirely!!!
Oct 10, 2003, 02:48 AM
Well in that case, keep it up, we all want MS destroyed both totally and entirely :)
Not sure about the taking over of the world though... :(
Oct 10, 2003, 03:40 AM
BTW "reversed" is normal in a PB - it just refers to the layout of the RAM slots.