Cant find the needed RAM. Need Help.

Is this a laptop? The speed you'll need to look for is 800MHz (DRAM frequency x 2), but I'm guessing you'll need 204-pin DRAM for a laptop rather than 240-pin desktop RAM. Best way to ID it is to look on the data sticker on the RAM stick itself.

In that case, she's probably going to need a stick similar (not recommending this particular one) to this:
http://www.memory4less.com/m4l_itemdetail.aspx?itemid=1440681394&partno=MT18KSF25672PY-80B&rid=90&origin=pla&gclid=CIndl6ymw8MCFZOBaQoddp8ALw

If it's an OEM (store-bought) system, if you can tell us the make and specific model and which OS she's running (i.e. Windows 7 32-bit, 64-bit, WinXP etc), we can make a more specific recommendation. At a guess, it will probably be cheaper to just replace it with a matched set that's compatible with the motherboard and CPU, and get more capacity at a higher speed (i.e. 2 x 2GB, 1333MHz or similar). Less likely to run into RAM compatibility conflicts that way too - mixed DRAM sticks don't always play well together.

Unselected solution for you.

The spd tab of cpu-z will give a partnr.,maybe give that here.

Saying 2gb in single channel doesn't mean necessarely that only two gb's are in the system,can also be 2x2gb in single channel if having four slots.



Somehow read over this.

As I said in my previous post, the DRAM I linked was not recommended, I just used it as an example of general technical specs - it was the first listing I found that matched the main specs listed in the CPU-Z screenshot. The benefits of having faster, larger capacity RAM are not the sole domain of gamers - anyone who likes to have lots of programs or apps, or browser tabs in particular, open at the same time will recognize an appreciable performance increase. 8GB is considered a standard for gaming, but it's also a good number for a non-gaming general user that spends lots of time on their PC. For a general user, 4GB is about as low as you want to go. (It's not directly comparable, but the DRAM listed in my signature is an example - I don't game very often, but make good use of 16GB of DRAM in other applications. At any given time, I'll be running two browsers with 15 or 20 open tabs, plus half a dozen programs.)

A few points to keep in mind:

-The DRAM listed by Crucial (a very reliable compatibility checker, and manufactures good main-stream DRAM) is compatible with your sister's PC (motherboard and CPU), not necessarily with her current DRAM. Mixed DRAM sticks are not always compatible with each other, even if they're identical brand, speed, size, and timings. If they have different specs, as in the case of the DRAM you ordered for which the size is the only commonality, the possibility for conflicts goes up. If they don't work together initially, they can sometimes be made to work by tweaking the timings and voltages in BIOS, but I'm guessing your sister may not be prepared to do this. If, through tweaking, they can be made to work, they're most likely to work at the settings for the least capable DRAM stick. In this case, the ordered stick is 1600MHz CL11 and the original stick is 800MHz CL6. IF they can be made to work together, it'll probably be running at 800MHz CL-11 or -12, so basically the lowest common denominators (or the worst of both worlds).

-Buying an identical stick, while less likely to experience DRAM conflicts, doesn't guarantee there won't be conflicts. It may also not be the most cost-efficient choice. If the original that you're trying to match is old, it may actually cost more than newer, better DRAM because the older it is, the fewer manufacturers (if any) will still be making it, resulting lower supply and higher prices. If you look at the cost of DDR2 DRAM, you'll see what I mean. Your sister's current DRAM is barely one step removed from DDR2.

-The surest way to make sure you have sticks that will play well together is to buy a matched set. In other words, a set that is from the same production batch that has been binned, tested and sold together in the same package.

I would recommend one the three following options:
1. Cancel your current order and find another stick that matches the current one as closely as possible.
2. Order an additional stick the same as the one on order, and use the pair to replace the current one instead of adding to it. It'll still be a mixed set, but they'll be much more likely to work together. She'll also have DRAM running at 1600MHz instead of 800.
3. Find a matched set that is compatible with the system to replace the current stick. It might be slightly more expensive than your current order, but will be much better in almost every sense. There are multiple 2x2GB sets on Amazon GE that will fill the requirement for under 50 EU.