Windows 7 - Installing additional RAM - need to know speed, type and size.

Hello,
I have 2GB RAM on my Windows 7 Ultimate 32-bit. I would like to buy additional 2GB RAM making a total of 4GB. I know that 32bit Windows 7 will not detect 4GB of RAM so ill be installing 64Bit version. I have a AMD athlon x2 dual core 5000+ 64Bit processor at 2.60GHz. I just opened up my chases to find out what type of RAM I have and also did a "Crucial Scan" which tells me I have a DDR2 PC2-6400, DDR2 PC2-5300 type of memory. I read somewhere that I need same type of RAM for better performance. My RAM card's label says it is a 2GB 2Rx8 PC2-6400U-666.

I need to know if I should install the same PC2-6400U-666 RAM in another slot or I can even use PC2-5300? which one is better? My RAM card labels does not show the RAM speed.

Also the Crucial Scan says that I can install a maximum of 4GB RAM. But is it 4GB per slot of the manufacturers maximum is 4GB?

My Crucial Scan:


Edit:
You can get all information you want about your RAM with a little tool called CPUZ even without opening your CPU case,
(Just for people who will have same problems in future)
My RAM details:

If you want the best results, I would go in one of two ways. I'd either pull he existing chip out and buy the identical one....or just buy a new 2x2 GB kit. Either way, for best results and best chance of compatibility, you'll want identical chips.

Given the link, it means you have two slots in total, that can accept up to 2 GB per slot, for a total of 4 GB.

I like crucial. Max of 4 Gb kit with 2GB per slot. 6400 is faster than 5300. You will want to match these, to get the best performance.

Not necessarily. Just because the memory is capable of a faster speed, doesn't mean it will actually run at that speed. The BIOS will determine that, and if it is an OEM system, there's a chance that the user can't set any custom options or speeds. As long as the chips match, there won't be anything to worry about.

I agree with DeaconFrost.

Your maximum RAM capability is 4GB so there's no point in switching to a 64-bit version of Windows.

I'd be inclined to buy 2 2GB matching sticks of RAM too.

Agree that I probably wouldn't switch to 64-bit for a slight memory gain. But Deacon, the architecture does support both speeds. If you mix chip speeds, I think it defaults to the slower speed.

Thank you for the replies

But wait, a 32Bit Windows 7 OS supports 3GB to 3.5GB RAM but is that for each slot or considering both the slots? Purchasing 2 2GB RAM 's would make the total to 4GB and my OS won't support it?

Yes, if you mix chips, the slowest speed is what will be used...but you are missing my point. If the BIOS decides to run the chips at 5300, based on multipliers from the processor, it won't matter if you use faster memory or not. In most OEM systems, you can't manually set the memory speeds.
I think you're missing something as well. Windows memory support has nothing to do with the slots. The maximum memory is governed by the motherboard. If your board says 4 GB is the max, than that's it. Windows will then have a limit based on what is available to it. For example, if you had a newer board that allowed 16 GB of memory, and you installed Windows 7 x86, you still wouldn't only see a max of 3.25 or 3.5 GB.

If you decide to install 4 GB of memory and stay with Windows 7 x86, you will only use 3.25 or 3.5 GB of memory. If you switch to x64, then you will be able to use all 4 GB. That decision is solely up to you.

The part we're trying to get you to realize is that you have two slots, capable of using a maximum of 2 GB per slot, as detailed in your screenshot. So, that means you will have a maximum of 4 GB available to whatever OS you decide to install. Once you get past that, then you will have to decide on an OS, as non-x64 versions will only see a portion of the 4 GB.

I understood that I have 2 slots 2GB each and I can install a maximum memory of 4GB
So either I can buy 2 2GB new RAM cards or a single one similar to my original.
Thank you everyone who helped me.
(I will switch to x64 version of Windows 7 to use the full 4GB(already have a installation copy of it ))

Yes, that's exactly it. If you plan to buy just one chip, I suggest trying to get an identical one. Anytime you mix chips, there is always a chance they won't "play nice" with each other, even if they are both compatible with the motherboard.