pc wont start help

[johnclean]

Operating speed - 2.4 GHz - 64bit windows 7 
Graphic - SAPPHIRE HD 5450 1GB DDR3 (400w ps required) 
PSU - 300w 
got basic knowlagde of PC repaires so Excuse my Mistakes 
changed graphic card year back without checking Watts. 
Added 2gb RAM to PC 2x1gb, 1x2gb RAM(4gb) 
That was 1year back everything was working fine until Recently I started gaming alot. L4d, Dota, 
Got Payday and started lagging So to Run this game smooth I thought i will upgrade My RAM and correct my mistakes of 2x1gb, 1x2gb RAM(4gb). 
changed to 2x2gb PC didnt start, Fan running. thought RAM was faulty so i checked each RAM by inserting indicivally 1 RAM Didnt work other did. so i Kept just 1x2gb RAM pc worked fine(slow/ freeze). 
brought 2 new RAM. inserted 3x2gb RAM now pc wont start. Desktop back green light is on/flickering. Changed RAM back to 2gb. still same nothing what is wrong ? 
Also Before All this RAM mess My Wireless Adapter kept getting DC. idk if it was because it was far. But that just started recently same time as RAM failures. 
Is it my PSU or Motherboard.

[OnekillWalter]

thank you for the ram story, but we need more information on your rig. the complete pedigree would be nice. your psu could've broke and damage your mobo. as far as I know it could be anything.

[johnclean]

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[johnclean]

thank you for the ram story, but we need more information on your rig. the complete pedigree would be nice. your psu could've broke and damage your mobo. as far as I know it could be anything.

 

thank you for the ram story, but we need more information on your rig. the complete pedigree would be nice. your psu could've broke and damage your mobo. as far as I know it could be anything.

This is My PC. I just got basic PC knowledge.

http://h10025.www1.h...ct=3542411#N480

Issues just started recently Lagging games. PC freeze Wireless adapter disconnecting Lot of time. 

[OnekillWalter]

as per the description of your computer symptoms, it appears the psu/mobo might be faulty. might be time to salvage the remaining parts and buy another budget pc.

my gf has the same pc, given by her dad. and i hate this case, no place to work. i wouldn't bother buying replacement parts, I would retire that old lady. she deserve a rest. permanently.