Help with my SSD upgrade

[lokopragaloko]

I have an Xbox 360 Slim with RGH2 and a failing 250GB HDD that I want to upgrade to a 480GB SSD.
But when I format it in the console's Dashboard, it only shows 120GB available.
If formatted as a USB drive, the correct size appears, and I've already verified that the drive is legitimate.
FatXplorer also shows the correct size, but files copied through it don't appear on the console, Only those copied by XeXMenu and Aurora.
Is there a patch missing for my console?

 

[DinohScene]

Are you using it through a USB connection or directly to the SATA slot?

RGH machines are as simple as shoving a new drive in, formatting it on the MS dash and it'll immediately allocate all available space as your storage partition.
The HDDX partition (original Xbox software) needs to be restored manually.

 

[Hippocampus_Hamster]

May also be a bad drive, if its not brand new. Or maybe the Xbox just doesn't like it.

What brand is the SSD? It shouldn't make much of a difference for a hacked system, but if its an off-brand/Chinese drive it may be false-flagging the actual amount.