System crash after RAM replacement

this has been covered before a couple of times, but here goes.

first run a hardware test (on your install dvd)
if that says one of the ram sticks is bad your problem is solved.
if all is good according to the hardware test, remove one of the sticks of ram and use the computer normally, if it works swap the ram for the other stick and try again. If you get a lot of errors then that is the bad stick of ram.

According to MacRumors's guide, the Apple Hardware test isn't all that great, but it should probably still be the first test to try.

A better memory testing app for Macs is called Rember. There are two ways to run Rember. Through OSX the normal way or by using single user mode.

1) The easy way in OSX: Run rember just like any other application. Since you're currently running the Mac OS X, lots of memory is currently in use meaning that you can't test it. A better, but slightly more complicated way to test your memory is to use the second method since it uses far less memory.

2) The command line way: This method is a bit scarier since it involves booting into single user mode and using the command line. This process is simplified by putting the Rember application at the root of your hard drive. Hold (Command) + S when you turn on your computer. Type "cd contents/resources". Now type in "./memtest all (passes) (log)". Don't forget the period.

Where I wrote "passes", type in the amount of times that you want the test to run. Where I wrote "log", a log will be written if you type in "-L", otherwise it won't write a log.

The default # of passes is 1, so if you want to quickly run the test without writing a log, you can just type "./ memtest all".

To find the log, in OSX, go to the folder where you stored Rember. Right(control) click Rember and then click "Show Package Contents". Go back to the folder I mentioned earlier and you will find the log named "memtest.log".

apple uses all sorts of ram, they just charge more for it.

It might only be one bad stick

I have a Imac 27" i7 and it has been crashing randomly for the past year, mostly when loading memory intensive things. I finally got around to removing the added memory and it is now slower but not crashing anymore.

I purchased:

1 x Kingston 8GB (2 x 4GB) 204-Pin DDR3 SO-DIMM DDR3 1333 Laptop Memory Model KVR1333D3SOK2/8GB from newegg.

I will be looking into a different brand of memory soon since it is noticeably slower, but I prefer not crashing over running slow.

It did have 12gb's but is now down back to 4gb. I am not sure if I could have left an electrical charge when I installed it originally since I didn't use a wristguard.

I did fry my toshiba netbook motherboard when i installed extra memory. It worked after I installed it, and I plugged it in to charge and it shorted out the motherboard. Toshiba replaced the motherboard.

I purchased a static wristguard so I do not have this issue anymore.