Corsair VS1GSDS400/EU 1GB in Duo

Yesterday put Corsair VS1GSDS400 1GB RAM chip into my Duo v1 (SPARC) mk2 (vel. RND2000 v2). Firmware 4.1.10. I just bought this RAM chip brand new from the big shop yesterday, so I think it's not the old make of this RAM chip (but maybe it spent few years on the shelf before I came to grab it).
Unit booted normally from the first time showing 1024 MB RAM [2.5-3-3-7].
Then it worked under load all night. In the morning I run memory test (only once) and passed OK.
By the way - it's not really necessary to unplug power cord from the ReadyNAS after 8 stage memory test is finished okay. I just pressed the power button for 2 sec. and unit booted to it's normal state. It works now for some more hours loaded with SMB, FTP, Wordpress and something more and OK.

P.S. After one week I returnet the memory chip to the vendor. Why? There was problem with rebooting ReadyNAS - it hanged. With original memory chip it's ok.