Computer memory

[furrycheeky]

I am looking to upgrade my PCs memory from 1 gb to 2 gb. I want to match the new with the old and my original receipt tells me I have 2X 512 DDR 3200 with 184pins. Thats all Ok so far, I went to a few sites and found these are available, and in fact the Crucial Memory shop has an online checker that checks the ram you have for you.
I have now almost got the ability to match with the ram I already have, but then I saw an advert mentioning a way of rating memory I have no idea how to check what I have already.
2 rams I am considering are rated thus: 1 is 2-2-2-6 and the other 2.5-4-4-8.
I have no idea what this means and should I be worried to get this matching the ram already in my machine?
If I need to match up exactly how can I tell what I already have? All the memory testers only tell me the info I posted at the start.
Any help appreciated.

[Ethel]

If it puts your mind at rest I did the scan and bought memory for my pcs from Crucial and was very happy with the price and service.

The memory was compatible, it arrived next day and took 10 minutes from start to finish.

I never put any information in the Crucial scan, except the make and model of my pc, and to be honest was very nervous - I had never opened a pc before. I would use them again.

[vehelpfulguy]

If you are running XP Pro or XP Home I doubt you will gain very much from increasing your memory above 1Gb.

[vehelpfulguy]

How may memory card slots have you on your motherboard ?.

If you have 4 you should be OK.

Many have only 2 and if you are running 2 x 512 then they are both full.

If you have only 2 you will need to buy 2 x 1Gb to get the memory you want.

[OBonio]

As Ethel mentioned, crucial offer a service that should tell you what memory is compatible with your system and how many free slots are available :

http://www.crucial.com/systemscanner/

[furrycheeky]

Thanks for the ideas. I have 4 slots with 2 free, I just wondered what if any difference there is between 2-2-2-6 memory and 2.5-4-4-8?

[beebrook39]

The blocks of four figures refer to the "latency " of the memory module...the following will give you some idea of the meaning....As with almost all latency issues, the lower, the better. When picking out SDRAM to buy, these four measurements are only important in high performance computers. RAM speeds are given by the four numbers above, in the format "tCAS-tRCD-tRP-tRAS". So, for example, latency values given as 2.5-3-3-5 would indicate tCAS=2.5, tRCD=3, tRP=3, tRAS=5. (Note that .5 values of latency (such as 2.5) are only possible in Double data rate RAM, where two parts of each clock cycle are used)

Most computer users don't need to worry about SDRAM latency, because the computer can handle the auto-adjustment to RAM timing based on the ROM inside the RAM packaging that defines the four timing values, decided by the RAM manufacturer. Although the SDRAM latency timing can be adjusted manually, using lower latency settings than the module's rating (overclocking) may cause a computer to crash or fail to boot.

[furrycheeky]

Many thanks for that.