Added RAM PC won't boot

[ElderGodElmo]

So my grandma gave me her old PC. Bad PSU. Replaced PSU, threw a low profile graphics card in there. It originally had a 1 gb stick so I bought a 2 gb stick to add on. It will boot into windows fine on the 2 gb OR the 1 gb but not both at the same time.

 

[Yoplait95]

More specifics plz.

 

[i7Baby]

You can't mix ram up and expect it to work. That's why the mobo manufacturers specify tested ram kits.

 

[ElderGodElmo]

I'm not near it at the moment but the mobo supports up to 4gb. both sticks are PC2-6400 at 800 MHz. Pentium D, dual core. Graphics card is ATI Radeon HD 3650.

 

[i7Baby]

But one stick is a different size to the other. And there's probably other differences. They aren't part of a tested ram kit.

 

[Tradesman1]

Really need the mobo and the CPU, if it has 4 slots and maxes at 4 GB then it prob only uses 1GB sticks - otherwise initial thought is the two sticks just don't want to play - and if it's a prebuilt PC there's little you can do since the BIOS is prob locked