Need help on putting more memory in comp

[willy ray]

I have a dell e521 I have 2 seperate memory modules 1 serial#kvr667d2/1gr #2 serial #kvr533drn4/1g are they a pair will they work in my desktop

 

[Pyroflea]

They appear to be different frequencies judging by the serial numbers. However, they will still work together; your BIOS will automatically match their speeds.

 

[andrern2000]

...but at slower speed @ 533 Mhz by default unless you set it manually to 667 Mhz at BIOS.