Originally Posted by boonie2
Does anyone know of a site that shows what chips different memory manufacturers use in their memory ? i.e ocz , g-shil ,mushkin , corsair etc? the reason im asking is I got a set of Mushkin preformance ram ddr500 today and CPUZ and EVEREST both show them as pc3200 ddr400 , trying to see if someone pulled the heatspreader trick on me
Some clarification is in order.
For DDR, JEDEC specifies a peak spec of DDR400. This takes into account only STOCK reference clocks (200MHz on the HTT Clock/FSB), where the RAM frequency runs 1:1 with the reference clock. By definition, anything over the stock reference clock is an overclock, and JEDEC standards do not extend to overclocked settings.
Here is a breakdown of JEDEC's DDR SDRAM Standard Frequencies:
Click this link
- DDR200 = 100MHz x 2 = PC1600
- DDR266 = 133MHz x 2 = PC2100
- DDR333 = 166MHz x 2 = PC2700
- DDR400 = 200MHz x 2 = PC3200
for a more complete description of JEDEC technical standards for DDR.
An interesting note from the following link: All RAM speeds in-between or above these listed specifications are not standardized by JEDEC — most often they are simply manufacturer optimizations using higher-tolerance or overvolted chips.
RAM manufacturers that produce RAM with DDR ratings higher than any of the JEDEC standards are only required to program their SPD chips up to the JEDEC peak of DDR400. However, because of the price premium consumers pay for optimized RAM, most (if not all) RAM vendors who sell "overclocked RAM" such as DDR500 modules guarantee that their product can run up to that speed.
Note, too, that the RAM is not overclocked until the reference clock itself is overclocked, especially if the RAM runs 1:1 with the reference clock.
The fun begins, though, when the CPU frequency (which, of course, is the product of the CPU multiplier x the HTT Clock/"FSB") is much higher than what the RAM max clock potential is. You run a divider in these cases. What happens then is that the RAM clock is slowed down so that it can run in step with the CPU clock. And what might often happen is that you have to really underclock your RAM just to maintain your CPU speed up.
Here's a real world example: Let's say your CPU can run stable at 2.75GHz. You have DDR500-capable RAM. Let's say your RAM can only do 250MHz (exactly DDR500) maximum. Let's further say that you have a 10x CPU multiplier. Obviously, then, the HTT Clock needed at the default CPU multiplier setting (10x) is 25MHz greater than what the RAM max clock can do (250MHz).
You then useGogar's Athlon64 OC Optimizer
(one of my favorite OCing tools) to find the best possible settings. (Incidentally, this is also why I insist on finding your various sub-systems' maximum potential speeds; you take the guessing game out of knowing what your parts can really do.)
Thorough stability testing will then be the final step, when you find out if your mix of settings will work.
Hope this long post helps, people.