Memory Problem ON P4S533

I used to have ONE PC2700-512MB Memory on my board (P4S533)

The problem comes when I'm playing an online game (namely Lineage2)

I was trying to install additional RAM, so I installed another PC2700-512MB
and then the game will crashed once a while, while it runs prefectly fine(though laggy) with just 512MB(doesn't matter which one of two RAM i use) I've consult with the game's tech-support, they say if it happens whenever two good RAM are used together, then it should be one of the sockets that's bad. What does that means? is there any other possibility? Or i have to change the MotherBorad??T_T

ps. I've tried a third RAM, and currently the two memory are both Samsung chips, so I don't think it's about conflict between Memorys...

Hi Welcome to the forums!
I have the p4s533 on my #2 rig. I don't game it much anymore caus of the new one but i use it alot for networking. Sounds like your ram problem might just be the mobo. But test all the sticks anyway. I had a new stick of the same stuff arrive bad and wouldn't even post. I had to rma it. Are you OC'd while gaming? My system had issues when overclock too high.
Good Luck

or u might wanna borrow a ram, different brand that u could test ur system, maybe that type of ram isnt jst compatible with ur pc...