"I ALREADY answered for your question about What kind memor. #28"
yes you did, one time in a 7 page thread, you did indeed say exactly what kind of memory you have. Hopefully you can forgive Thrash for not being aware of that.
"This is not a new purchase I have them already about one year and they were working perfect."
Yes, they were working perfectly at 2.75GB useable. They have been at 2.75GB usable since the day you got them. The odds that they were at 4.0GB usable a month ago then suddenly dropped down to 2.75GB are infinitesimally small.
You really need to update your profile system specs. People here who try to help you (for free) are looking at your hardware specs and thinking you are on an ASUS P5K Deluxe/WiFi-AP motherboard. The fact that you said once, in a post a few pages back, that you are actually running an Asus PTGD1-LA (HP Goldfish3), is probably something that few here are aware of. If your profile specs were accurate for your memory and your motherboard, you would find that people are better able to help you.
Having said that, neither HP nor ASUS have published a Memory QVL for that board that I can find.
Power supplies all work with any system if they are rated high enough. Graphics cards work with any system they can attach to. Same with Hard Drives. But memory is different! Because of the unique timing challenges of dual channel that I outlined in post #55, memory is not compatible with a motherboard just because the specs match, it MUST be qualified by the maker of the motherboard for you to be sure it will work perfectly. Your memory is "Value Select", which is a low-end product. It is obvious that it is not fully compatible with your motherboard. No biggie though, because its also not the problem here.
Here's what I think. Your computer slowed down a few days ago and in post #14 you concluded that this is because you are running with 2.75GB of memory instead of 4.00GB. I assert the following as facts:
1) your computer is running slowly and/or poorly
2) Your system has been running with only 2.75GB since the day you put in the memory, which was not a problem a year ago and is not a problem now.
3) Memory is not the problem here. There is some other problem and we need to start over.