Cook1, I have the same memory which arrived earlier this week. When I run 1:1 with cpu at 250MHz with all timings on "Auto", except command rate which I set to 1T, the tCL-tRCD-tRP-tRAS timings default to 3-5-5-9 on this Epox board. Here's a
screenshot of all the readings.
When I manually set tCL-tRCD-tRP-tRAS to 3-4-4-8 I couldn't POST unless I changed the "Read Preamble" from 5.5ns to 6.0ns. The settings on this
screenshot are memtest stable. Note that the vdimm is 2.75v on Auto setting so if you're running on 2.5v, you might be too low.
My cpu maxes out at 280HTT on 1.55v vcore. At this speed I have to run the RAM on a 166 (5:6) divider which on a x9 mutliplier gives 229MHz. Since this is underclocking the RAM frequency I am able to tighten up the timings to 2.5-3-3-6. I also lowered tRFC a little from 24 to 20. Any lower fails memtest. To be sure this is stable I have set the vdimm to 2.8v which actually gives 2.85v due to overvolting by the board (not excessive enough to worry about). Here's a
screenshot.
In order to find what gave better performance, speed or timings, I used 3DMark05 as my benchmark tool & tested using my prefered 166 divider (229MHz) and also on a 183 divider using A64Tweaker (252MHz). The results below, show that the tighter timings at the lower frequency out-performed the higher frequency with default timings in both game and cpu tests. The game score increase is negligible however, and would translate into an unnoticable effect in real world use. The increase in bandwith with the tighter timings is noticable in tasks like Windows & application startup. Not done any encoding or other heavy duty stuff so cant comment on that I'm afraid.
MHz_Timings__CPC_3DMarks_CPUmarks
229....2.5-3-3-6...1T.....6458.........5387
252....3.0-4-4-8...1T.....6454.........5233
229....2.5-3-3-7...1T.....6454.........5101
229....3.0-4-4-8...1T.....6447.........5132
Incidentally, when I tried to overclock the memory frequency I could not get memtest stable at 260MHz. This may have been due to me not having loosened timings enough or maybe just bad luck. It might have been nice to have got them over 270MHz, like in some reviews I've read, but I'm not too bothered though because the lower speed & tighter timings are giving good enough performance.
So, what speed are you hoping to run your HZs? You should strongly consider going lower than 250MHz & tightening the timings. And give them more than 2.5 volts.
I am planning on doing some more testing with my HZs and may start a new thread with all the findings. I'll keep you posted.
Steve
EDIT: Fixed links