Thanks, I'll keep you posted.

I have reinstalled the original memory and it works fine. With the new memory installed along with the original memory the computer recognizes 4gb but only 2 is usable. With just the new memory installed the pc refuses to boot.

Its not a slot issue because I have tried the original memory in all slots and it works fine.

I have removed and refitted the ram numerous times, I would think that I would get it right at least once so I guess its not an install problem.

I had faulty ram originally which resulted in the computer refusing to boot and it would just beep. Returned this to the seller and they replaced it.

I'm guessing that leaves me with incompatible! The seller did state it was compatible with the dell 545 but then they would wouldn't they!!!

Thanks for the help, I'll contact the seller and see what they say.

Most likely it is not compatible.   You bought slower memory and your Samsung will default to the slower speed (6400 vs 5300).  Different speeds can still work together, however.  Dells tend to be picky about memory which is why I normally just by Crucial.  HERE is there memory if you need it and can return the other.  HERE is Kingston's compatible memory, but I can't tell if it is different or not.  

rosans

Good luck and I hope it works out for you.

Bev.

rosans

There are basically four reasons, why memory does not work (1) RAM not compatible to the computer (2) Faulty RAM (3) Bad memory slot [rare] (4) RAM not installed correctly.

Sounds like the memory is not compatible.

Reinstall only the original default memory and see if the system starts without any issues.

Bev.