I am a big fan of transintl.com. They've been really nice to me, and their site has some good info.
pc100 Ram is good for use in pc100 machines and slower.
pc133 Ram is good for use in pc133, pc100, and slower.
at 100MHz, cl2 is 6ns, cl3 is 8ns, and the rare DIMM will come in at 7ns. 6ns or cl2 is the fastest at 100MHz. at 133MHz, the math is messier.
This is a measure of compatibility and not of performance. 8ns, 7ns, 6ns or cl2, cl3, these are measures of performance. The sum up...
PC133 isn't higher performance, at just deals with 133MHz busses. To do so it may promise data in 3 clock cycles at 133MHz that at 100MHz it could promise 2. If you buy cheap RAM, you usually get cl3 or 8ns at 100MHz. I haven't been playing at 133MHz recently, but last I looked, everyone was delivering cl3 at 133. If the RAM is smart it may be able to do cl2 @ 100MHz and cl3 @ 133MHz. This is not the common case.
Usually RAM is set to just deliver in so many clock cycles, and making the RAM compatible with higher bus speeds means you can only guarantee data in 3 clock, not 2, and even if the bus speed slows down to 100MHz, the RAM still only promises data in 3 clock
At boot, your Mac will ask all RAM how fast it can deliver data, and set itself to the slowest one, so that if it needs data, it can be prepared for the worst case scenario.
All that said, when I popped in 2 different pc133 Dimms in my PC100 Mac, one showed up as 7ns, the other as 8ns, and the added RAM was way more important than the RAM latency. That was 64M to 576M, YMMV.
pc100 Ram is good for use in pc100 machines and slower.
pc133 Ram is good for use in pc133, pc100, and slower.
at 100MHz, cl2 is 6ns, cl3 is 8ns, and the rare DIMM will come in at 7ns. 6ns or cl2 is the fastest at 100MHz. at 133MHz, the math is messier.
This is a measure of compatibility and not of performance. 8ns, 7ns, 6ns or cl2, cl3, these are measures of performance. The sum up...
PC133 isn't higher performance, at just deals with 133MHz busses. To do so it may promise data in 3 clock cycles at 133MHz that at 100MHz it could promise 2. If you buy cheap RAM, you usually get cl3 or 8ns at 100MHz. I haven't been playing at 133MHz recently, but last I looked, everyone was delivering cl3 at 133. If the RAM is smart it may be able to do cl2 @ 100MHz and cl3 @ 133MHz. This is not the common case.
Usually RAM is set to just deliver in so many clock cycles, and making the RAM compatible with higher bus speeds means you can only guarantee data in 3 clock, not 2, and even if the bus speed slows down to 100MHz, the RAM still only promises data in 3 clock
At boot, your Mac will ask all RAM how fast it can deliver data, and set itself to the slowest one, so that if it needs data, it can be prepared for the worst case scenario.
All that said, when I popped in 2 different pc133 Dimms in my PC100 Mac, one showed up as 7ns, the other as 8ns, and the added RAM was way more important than the RAM latency. That was 64M to 576M, YMMV.
