System doesn't boot up after Memory(Ram) upgrade.

I recently upgraded my memory to 2 gigs of Ram with 1 gig each, both with same brand (Crucial). THey were purchased separately from Ebay. The 2nd card(purchase) is the one I am blaming and diagnosing as being defective, however I may be wrong. I have a SONY SZ110 and last night it refused to boot up. I got 2 or 3 seconds of the hard drive light then it went dead, with only thing left was the Power light and the bluetooth light. After giving up I was on the phone with SONY support (told me to start up and hold F2 key, nothing happened), they claimed it is possibly a motherboard issue but before that they told me to re-install the original 2 (512mb) of ram, which I still luckily had. At first it didnt work, but then I realized I didnt insert them and lock them correctly(from being nervous that I lost all my info, I wasnt focused), eventually the system boot up with the original ram. I then wanted to figure out if it really was the motherboard or the recent 1 gig I purchased. SO I re-installed it, in each slot and it caused the system to not boot up again. I then re-installed the 1 gig that was good (1st purchase) and a 512 and it works fine. My question is...
1) Can a defected card of ram in one slot cause the system to not boot up?
2) No ram (empty slots) will prevent the system from booting, correct?

I have diagnosed this myself with the 2nd purchased 1 gig being defected or not compatible, although Im sure its the same exact as my first purchase.
I want to know because SONY still thinks I'm sending them my laptop for what they think is the motherboard at fault. They mailed me a pre-paid box and I dont want to send it out since Im on it not with the 1st purchased 1 Gig of Ram, and the defective?? one layin on my desk.

 

1) yes defective RAM can cause the system not to boot properly. And if it works in all configurations except with that one stick I'd guess it's a bad stick of RAM.

2) computer should have no problem running with one slot empty. Never tried it with a Sony, but lots of computers come from the factory with only one slot filled.

 

well it didnt boot up AT ALL with this one stick. Boots up fine without it and with one slot totally empty so my conclusion is the stick and therefore I will not ship it to SONY since they assumed it was a motherboard issue. I just hope I'm right.

 

What you are going through is pretty common. Ram can be defective or just picky on particular systems.

A great way to check ram before booting up with it the the first time is with Memtest86. Download and burn the .iso image to a cd, set your computer to boot from the CD, put the disc in and boot it up. It's very easy. A great tool for overclocking as you can test different settings, but it also works as a simple "is it working?" test.

Memtest will start a series of tests, if you get errors then you know something is broken or incompatible. 99% of the time good working, compatible ram will have no errors.

Ram that is Defective/incompatible/picky/overclocked too far can corrupt your Windows system files if Windows makes it far enough into the startup process. Obviously your system didn't get far enough for that. You want to make sure you have important stuff backed up when fussing with ram.

 

Definitely defected RAM. Do as djspl says. Run memtest86 or memtest86+ for a few hours and see if you get any errors.