How to find information about the RAM?

Check out this How do I detect the RAM memory chip specification from within a Linux machine question.

This tool might help:

http://www.cyberciti.biz/faq/check-ram-speed-linux/

$ sudo dmidecode --type 17 | more

Sample output:

# dmidecode 2.9
SMBIOS 2.4 present.
Handle 0x0018, DMI type 17, 27 bytes
Memory Device
        Array Handle: 0x0017
        Error Information Handle: Not Provided
        Total Width: 64 bits
        Data Width: 64 bits
        Size: 2048 MB
        Form Factor: DIMM
        Set: None
        Locator: J6H1
        Bank Locator: CHAN A DIMM 0
        Type: DDR2
        Type Detail: Synchronous
        Speed: 800 MHz (1.2 ns)
        Manufacturer: 0x2CFFFFFFFFFFFFFF
        Serial Number: 0x00000000
        Asset Tag: Unknown
        Part Number: 0x5A494F4E203830302D3247422D413131382D
Handle 0x001A, DMI type 17, 27 bytes
Memory Device
        Array Handle: 0x0017
        Error Information Handle: Not Provided
        Total Width: Unknown
        Data Width: Unknown
        Size: No Module Installed
        Form Factor: DIMM
        Set: None
        Locator: J6H2
        Bank Locator: CHAN A DIMM 1
        Type: DDR2
        Type Detail: None
        Speed: Unknown
        Manufacturer: NO DIMM
        Serial Number: NO DIMM
        Asset Tag: NO DIMM
        Part Number: NO DIMM

Alternatively, both newegg.com and crucial.com among other sites have memory upgrade advisors/scanners that I've used regularly under Windows. Some of them were web-based at some point, so you could try that, or if you could possibly boot into Windows (even if temporarily) it might help.

Not sure what the results would be under a Windows VM, and unfortunately I am currently running Linux in a VM under Windows 7, so can't reliably test for this myself.

I do realize that this doesn't give you necessarily exactly what you asked for .. but perhaps it will be of use none-the-less.

Just run

lshw -c memory

The program should be in the lshw package.

Sometimes it's good to know that you have alternatives, so here it goes:

# dmidecode -t memory