Only 2GB out of 8GB are useable?

[99nirc99]

Hi, ive recently purchased F3-12800CL9S-4GBRL memory stick and installed it on my mother board (Gigabyte mother board GA-P55-UD3L). I've already had 2 memory sticks installed
F3-12800CL7D-4GBRH (2Gx2). These 2 were installed on slot 1 and 3, and i put the new one
between them. How can i make use of all of the installed ram??? thanks...
EDIT: Forgot to mention I use Windows 7 x64 Ultimate.

[Tradesman]

While all three are 1600 sticks, two are speced to run at CL7 while the 3rd is a CL9 stick, you can experiment around, but wouldn't have high hopes of them playing well together

[99nirc99]

While all three are 1600 sticks, two are speced to run at CL7 while the 3rd is a CL9 stick, you can experiment around, but wouldn't have high hopes of them playing well together

So there is no chance for me to work with the 3 of them together?
And is it possible to take only one of the 2GB sticks out and try to work with the 4gb one
and the 2gb one? If not i just purchased a stick that would'nt work...

[99nirc99]

So i've got another possible solution. If i buy another F3-12800CL9S-4GBRL, can I replace
my two existing F3-12800CL7D-4GBRH with two of F3-12800CL9S-4GBRL??
If so i'll just get another one to have 4gb of ram...

[Tradesman]

You can give that a try, yes....there's no guarantee that they will work together, but chances are very good...any time you mix DRAM from different packages it can be problematic...it's always best to buy the quantity of DRAM you want in a single package, that way they are testeed to play together and if needed the XMP programming is there for that set

[99nirc99]

You can give that a try, yes....there's no guarantee that they will work together, but chances are very good...any time you mix DRAM from different packages it can be problematic...it's always best to buy the quantity of DRAM you want in a single package, that way they are testeed to play together and if needed the XMP programming is there for that set

Now i have a freaking new problem... I took out the new stick i bought and turned the pc on,
and now windows says i have 4gb of ram but only 2 are useable... What am I doing now?!?!
And on the other subject, is there a real different between this: http://en.gskill.com/en/product/f3-12800cl9s-4gbrl
which i have now,
to this?:
http://en.gskill.com/en/product/f3-12800cl9d-8gbrl
arent these just new packages to the same product? (just two of the same product)

[Tradesman]

The first is a single stick package and the second is a 2 stick package of the model....the advanced timings in SPD of the the second set will be different from the single stick advanced timings for XMP i.e. the tRFC on the single stick might be 48 or whatever and the tRFC on each of the pair will be about 88 as the more sticks you have the higher the tRFC needs to be