Technical problems after replacement of RAM

I went to purchase a new pc for 3-4 months ago, and had in mind to upgrade Ram later. For about 3-4 weeks ago I bought 4 GB ram and replaced the old 2 GB. I thought that they would match the components I had, but I check this with someone other than myself. I took out the old and into the new, and everything worked really well. The performance was heavenly.

When I go in to turn on PC was black screen and no contact with the USB devices. There was also a recurring longer beeping. I knew not what this is because, initially thought that it was the motherboard that had gone to ...
I searched as usual a little on google, and found that the longer the pipe the sound was an error in memory, and then think that this must be the error and not the motherboard. Think it is strange that this problem occurs so long after I switched ...

identified and put into the old memory chips, PC started in the normal way:
This is either the problem that the new pieces do not fit, or that they've been injured?

Technical info about PC:

Motherboard: Gigabyte 790 FX, AMD chip
Memory (old) 2048 Mbytes, 2 x 1 GB dual DDR2 1066 MHz
Memory (new) Dominator 4GB - 2 x 2gb DDR2 1066MHz PC2-8500 C5

Test frame with e.g. memtest86?

Beeping-interpretation should be in the manual, as well if you say what it's there

Not tested with memstest or the like, never heard of

Should check the manual, comes with more notice!

It should do with the time the system is built, So eliminating the hardware error with time. File Search is some shit

Beeping can generate Post error codes (search on this on Google). It may be warning about the heat. Check if the fan/heat sink seated properly.