adding (used) ram to PC

[knows_something]

As the title states, I'd like to add a 2x2GB stick of ddr2 ram to my pc. I have already got 2x2GB and i found some used ram sticks that would most likely fit in my PC. The reason I'm buying used is, because I found them for around 10€per stick and if I wanted it knew  It would cost about 25€per stick.  I have 4 slots and 2 are currently occupied. What i'm wondering is: 

1. Is all ddr2 ram the same speed?

2. Do all 4 sticks have to be the same?

3. Am I taking a huge risk buying used ram?

I don't know a lot about RAM so I would really appreciate it, if you could help me out. What's that talk about 2 channels on motherboards? I have absolutely no idea what that is and i probably need to know, right?

Thanks for your time and help.

[Clear17Mud]

ok so ddr 2 is different speed, but the slower one will slow the faster one down. Its not really that big of a risk, because I have only ever bought new ram once, and that was because I needed it and I couldn't find any used. all four sticks can be the same it doesn't really matter. They dont even have to be the same size... Its just more likely to work if they are all the same.

 

the only thing I have ever done that broke something was putting way to fast of ddr (1) ram into a motherboard that didn't support the ram...  Then magic smoke came out of the computer...

[knows_something]

this is my current RAM setup and as you can see I need the extra RAM. Would 2GB of used 800MHz stick for 10€ make a good deal?

RAM setup

[0wN3r]

Frist make sure your system handles >4GB RAM

[Fetzie]

As the title states, I'd like to add a 2x2GB stick of ddr2 ram to my pc. I have already got 2x2GB and i found some used ram sticks that would most likely fit in my PC. The reason I'm buying used is, because I found them for around 10€per stick and if I wanted it knew  It would cost about 25€per stick.  I have 4 slots and 2 are currently occupied. What i'm wondering is: 

1. Is all ddr2 ram the same speed?

2. Do all 4 sticks have to be the same?

3. Am I taking a huge risk buying used ram?

I don't know a lot about RAM so I would really appreciate it, if you could help me out. What's that talk about 2 channels on motherboards? I have absolutely no idea what that is and i probably need to know, right?

Thanks for your time and help.

1. No

2. yes

3. probably not

Do you have a 32 bit OS? If yes, you won't be able to use more RAM. Given the likely age of a system with DDR2 RAM, it probably has 32bit Windows XP (due to 64bit Windows XP being effing unstable and buggy).

If you already have two sticks of RAM, you're already using dual channel.

[HrutkayMods]

1. No

2. yes

3. probably not

Do you have a 32 bit OS? If yes, you won't be able to use more RAM. Given the likely age of a system with DDR2 RAM, it probably has 32bit Windows XP (due to 64bit Windows XP being effing unstable and buggy).

If you already have two sticks of RAM, you're already using dual channel.

Actually

1. No

2. Not really, if the other ram is slower, the faster will down clock to match the slower

3. exactly, probably not. when I was building my QX6800 build, I bought my DDR2 used, it all still works great

 

and yes you need to make sure your board supports more ram and you need to be running an x64 operating system

[Fetzie]

Actually

1. No

2. Not really, if the other ram is slower, the faster will down clock to match the slower

3. exactly, probably not. when I was building my QX6800 build, I bought my DDR2 used, it all still works great

 

and yes you need to make sure your board supports more ram and you need to be running an x64 operating system

re point 2: if the operating voltage is different then the respective sticks may be unstable even with modified clock speeds.

[knows_something]

i Have my PC specs in my description, but to sum it up:
core 2 quad q8300

and 64 bit windows 10

http://prntscr.com/9lsc1s >>this is my motherboard and it supports 16GB ram with various speeds. I have pc2 6400 5-5-5 400MHz RAM currently and have been looking at some used dimms for cheap. A lot of them are my type but some have 800MHz and one says 6400U as a type. Will that affect my PC or to be exact, will i short it out?

And if i decide to buy 2 extra dimms, am I going to have to tinker with my computer HW and SW or do I just insert it in?