Agent WD40 said:
First thing about RAM / Memory. You get your "DDR" speed from the HT speed x 2. So, when its saying its 245.4 its actually running at 290.8 which is almost PC4000.
Correction... 245.4 x 2 = 490.8MHz, but yes, that's almost PC4000 rated speed.
PC3200 = 400MHz (200MHz x 2)
PC4000 = 500MHz (250MHz x 2)
PC4400 = 550MHz (275MHz x 2)
They are referred to as PC3200, PC4000 etc due to the maximum bandwidth of the DIMM. PC3200 = max 3.2GB/s (or 3200MB/s), likewise PC4000 = 4GB/s.
The dual channel advantage of the socket 939 A64s is that you've got two memory controllers working in tandem, giving double the bandwidth (assuming you're using two matched DIMMS), so PC3200 dual channel = 6.4GB/s (3.2GB/s x 2), and PC4000 dual channel = 8GB/s.
Eventually, your memory will crap out when you're trying to push it too far. Your PC3200 memory, running at 245MHz (i.e. 25% higher than spec) is probably at its limit, certainly at the timings you're using.
To push your CPU further you will need to implement a divider on the memory frequency. Start with a 166MHz divider. This will reduce your memory speed to 83% (166MHz divided by 200MHz) of your HT frequency, in your case approx. 200Mhz (245MHz x 0.83), which is at spec speed.
A64s don't suffer from running the memory on a divider, so if you find you are crashing in games or Prime, then try this first. This will allow you to push your CPU to its max, which may be as high as 2.9GHz (~260MHz x 11). On a 166MHz divider, at 260MHz HT freq. your RAM will be running at 215MHz (430MHz DDR), giving you nearly 7GB/s bandwidth, and probably allowing you to run at decent timings without crashing!
Hope this helps.
Hav