有關外置RAM

there is NO SUCH THING as 外置RAM.
what we usually refer to RAM is the internal memory.
we can only add RAM (internal memory) that the PC can use to LOAD-n-RUN software/programs. (NOT external RAM).
that is why when checking your system memory (internal memory or RAM), it still reports 128MB only. as said before, the 256MB is NOT system memory (RAM).
to tell you a bit more [advance], computer (Windows) got REAL memory and VIRTUAL memory. in your case, your PC got 128MB real memory and perhaps 384MB virtual memory. Virtual memory is used in case you load more than 128MB programs/software, then your PC can still run them all BUT in slow motion.

恕我直言
點解要網上check硬件???
你部電腦check到有咪用得囉
乜你覺得網上要check會準過你自己部電腦check???

你玩唔到隻game
都未必關ram事
你都話你部電腦用左5,6年
都唔會勁得去邊啦
可能係其他硬件上既問題
有2個最大既可能就係cpu同埋display card
我想知你係點樣玩唔到
你形容下
仲有講埋你果隻係咩game
咁會易答d