I was looking at a MB manufactures qulified vendor list. Searching by the specs on the MB I found several memory chips that should work and none of them were on the list.
I then started comparing the different memory that I found versus the ones that were on the QVL to see the difference.
In one case the chips were exactly the same except for the command rating. Both were "Tested at the low latencies of (5-5-5-12-?). On one the ? was -T1 and the other -T2. The difference in price from the same MFG was around 100$ for 2GB of RAM.
Of course the more expensive one was the one on the QVL list. Just wondering what the odds that the cheaper one will work and what the difference between the testing is.
Reading the FAQ it states that the data is avaialable for one cycle on the t1 vs 2 on the t2. I would guess that this would slow the performance on the T2 version but how would this affect compatability?
It doesn't affect compatibility at all. It is just the cycle as you said, and the performance hit is pretty marginal as far as most games go, it may account for 3 - 6fps...correct me if im wrong? But the answer to your question is that the ram will be compatible regardless of the command rate as long as you get the correct type or memory at the correctly rated speeds!
Why do they test at different command rates then? And why would one be "Qualified" and the other not.
I can understand the premium price for the higher rated RAM, but am unsure why it would be tested at the lower rate unless the lower rate meant it couldn't operate at the -T1 level. If it can't operate at the -T1 level does that mean that it might cause issues with the MB/CPU?
No it shouldnt cause problems with it not operating at 1T, it will just set it auto to 2T. The info you are reading on it is just saying the best setting that either the motherboard or ram supports, so the motherboard may say 1T, but it still will run 2T. It just shows the better thing. Similar to most HDTV's where they advertise 720p, the tv will most likely scale to 1080i, but since progressive scan is better than interlace that is just what they advertise. even though both modes are supported. Hope that helps!