What DDR2 memory should I take to get everything running in tandem?

Question

RAM

Hello. There is a DDR 2 KHX6400D2/D6 2 gb memory stick (information from the stick itself) https://www.kingston.com/datasheets/KHX6400D2_2G.pdf,mother asus p5ql pro also xeon e5450 will be bought. First question: I looked at Avito, there is the same company, but the markings are different, for example, HyperX khx8500d2 / 1G, KHX9200D2K2 / 2G, Kingston HYPERX KHX6400D2B1K2 / 4G. What is the difference? The second question: if I take one of these (with a different marking), will the unit start up? Will everything work together? The third question: I remember, from old memory, what should ideally be taken so that there is the same marking in order to use it in two-channel mode, right? Is it worth taking the same memory? Fourth question: if they have the same markings, should they have the same amount of memory or not? For example, will it be possible to take to my 2 GB bar, for example, 1 GB (with the same marking) will work in two-channel mode?

Answer 1

You're right, ideally there should be identical memory pairs for dual-channel mode, especially true for DDR2, because XMP was only invented in DDR3.
If you set bars of unequal volume, then they will not work in dual-channel mode, their volume is simply summed up.
Choose memory of the same size with equal timings, this will increase the likelihood of error-free operation, especially since the motherboard is normal. Sometimes a simple rearrangement of the DDR2 strips in some places worked and everything started up.
DDR2 actually lies in services and IT admins are just mountains, go to the nearest service, maybe they will give it away for free or for a modest amount, prices for Avito are a little overheated.