Can anyone help?

Hi guys I have a dell e510 desktop that I've upgraded and I just ordered more ram an it came in yesterday, I had 2gb of ram but then I ordered another 2gb for a total of 4gb of ram. But my problem is that my computer is not reading the 4th ram stick, it only reads up to 3.0gb but when I install the 4th stick my desktop boots up but shows a blinking line and just sits there and won't even go to the dell screen.i try open ***. /male-perf-avis/ ;but could not do   Can anyone help??