I would try several things.
-First, make sure you have loaded the latest bios to the laptop from the Sony site. Go into the bios menu and see if all 8mb of ram are recognized there.
-Make sure each of the two memory simms are correctly seated and installed.
-Remove one memory simm and boot the computer to see if the single memory simm is recognized.
If it is recognized, remove that simm and now boot with the second simm alone. This will test to see
if possibly one simm is bad. Also try each, single simm, in the other memory socket to possibly see if one simm socket is bad.
Follow Antilope's post and post a screen shot of your resource monitor memory tab.
I don't think the memory would be bad since the OS recognizes 8GB but show 3.23GB usable. I would look under System Configuration, chooser the Boot tab then choose Advanced Options then look at maximum memory. I once had a similar problem running Windows 7 and the only way I could correct it was by putting a value of the correct maximum memory in the box and then saving that entry.
I have a similar problem with HP ENVY M6 notebook. if I install Windows 32bit I only get 4GB ram available but 986MB usable.. I then kept downgrading the BOIS from F.26. The only one that gave me around 3GB is F.12.
By the way, I have reported this issue to HP support last year. Alas, HP has not released a fixed BIOS yet.
I would advice you try the various BIOS versions to see if one would work. Also, state your computers brand, model and configuration so that other with similar setup may share their experiences.
MODEL: SONY VAIO F Series VPCF135FG
CPU: IntelR CoreTM i5-560M Processor 2.66 GHz with Turbo Boost up to 3.20 GHz
GRAPHICS: NVIDIAR GeForceR 310M GPU with 512 MB VRAM
BIOS is up to date and recognizes all 8 GB of RAM.
Both memory sticks are correctly seated and installed.
Both the sockets are OK, because, if I put back my old 2 sticks of 2 GB each, they work perfectly fine at their full capacity of 4 GB.
But as soon as I install the new sticks 2 X 4 GB , only 3.23 GB is usable.
If I install only one 4 GB stick, the computer does not boot at all, which ever slot or stick I use.
But if I install one of my old 2 GB sticks, the computer does boot and the memory shows 2GB.
I also tried under System Configuration, Boot Tab, Advanced Options, maximum memory by changing the value to 8192 MB but in vain.
Last edited by vedaban; 28 Sep 2015 at 05:20.
If the BIOS shows the full size but Windows does not, then it's likely a problem with Windows. I am assuming that the RAM is fully compatible with your hardware and that both sticks are identical.
Download the utility CPU-Z and see how that interprets your RAM and the individual RAM sticks.
If you can, run a Linux live disk and check the memory from there. This will doubly prove the fault is in Windows or not.
It's interesting that one stick of 2mb ram will boot the computer, but one stick of 4mb ram will not. There may be a hardware compatibility issue between your Sony laptop and the 4gb ram. Are you sure this 4gb ram simm is the exact recommended ram for this laptop?
What is the brand name and model number of the 4gb ram?
In looking up the specs for the ram, it seems to be what is recommended for the Sony Vaio VPCF135FG judging by what others are selling as ram upgrades for it.
But still, not being able to boot from a single stick of the 4gb ram doesn't seem right. There must be some hardware incompatibility and the laptop is only recognizing 2gb of ram from each of the 4gb simms. Why, I don't know, but that seems to be what is happening.
CORSAIR VENGEANCE CMSX8GX3M2B1866C10 DDR3L
SO DIMM 204-pin
1600 MHz /
1.35 / 1.5 V
8GB (2 x 4GB)
204-Pin DDR3 SO-DIMM
DDR3L 1866 (PC3L 15000)
Dual Channel Kit