Updating RAM Problems

So I'm trying to upgrade the RAM in my Sony Vaio VGC RC210G from default 2X 512Mb sticks to 1X 2Gb stick. I researched and found that the default RAM were PC2-4200 533Mhz. SO I got a 2Gb PC2-6400 800mhz that says it'c backward compatible with PC2-4200. The computer now runs 100X slower... I've tried looking into the BIOS to update them, but I cannot change anything besides time/date. Whats wrong here and how do I upgrade the memory correctly?!

 

From what i searched, your motherboard supports only the 533MHz speed. Sounds incompatible.

 

But shouldn't it automatically downgrade to support it as it's advertised as being backwards compatible?

 

Me again.
Your best shot would be 2x1GB of the PC4200.

 

Alright, too bad I can't return the 2Gb. waste.

 

Crucial.com is suggesting a PC2-5300:

http://www.crucial.com/store/listparts.aspx?model=VAIO VGC-RC210G

 

Most do, but that is a pretty good drop from 6200down to 4200.
Also, did you check to ensure they were both the same type? (ECC or non-ECC) It does make a difference.

 

Ok then, heres a PC2-4200 at TigerDirect:

http://www.tigerdirect.com/applications/SearchTools/item-details.asp?EdpNo=3424794&CatId=1647

 

IMO it would be better to have the 2x1GB setup. If something goes wrong with one, you still have something to work with. With 1x2GB stick, something goes wrong, just bend over and grab your ankles, because you just got *****.
Info I found showed 2GB as max anyway.