'Wizfrog' wrote:
| Just got a GA-P35C-DS3R with a Q6600 and some DDR2 8500 because the
| box said it was supporting 1333MHz FSB and 1066MHz memory... Well, not
| quite! It does support DDR3 8500 but only DDR2 up to 6400.
|
| So, should I return my DDR2 8500 5-5-5-15 and get a set of DDR2 6400
| cas3 or keep the DDR2 8500 and overclock it from the 800MHz the board
| supports?
|
| I'm not too sure how that works... Can I overclock the memory
| seperately from the CPU? I assume not, it depends on the FSB speed and
| muliplier, right?
|
| So, what's your opinion? Keep PC8500 memory or get lower CAS PC6400?
_____
Things are not what they seem; unfortunately the explanation that will lead
to an answer to your questions is not very clear.
DDR2 8500 is also known as DDR2-1066 and is rated for a 266 MHz clock. The
1:1 CPU Clock : Memory Clock you usually see is with a 1066 FSB is actually
clocking the memory at 533 MHz (the CPU is quad pumped, 4 X 266 MHz; the
DDR2 Memory is clocked at 2 X the CPU clock So, if you overclock your CPU
with a CPU clock of 400 MHz (rather than the stock 266 MHz) and a 1:1 CPU
Clock : Memory Clock you will get a 50% CPU overclock while the memory is
running at DDR2-800/ DDR2 6400 equivalent. The motherboard manuals from
various manufacturers use various terminologies for the CPU Clock : Memory
Clock ratio and for the Memory Bus speed. The exact same effect is being
described, but the words used can be different (and confusing.)
You are going to be setting the Memory Clock speed manually; you can set it
to any speed you wish. All the manual for your motherboard indicates is the
SPECIFIED memory speeds. You intend to overclock, so you are not going to
be using the SPECIFIED FrontSide Bus speeds, and you will likely set your
memory to something other than ANY of the specified speeds.
If you look at the sample memory speed setting in the BIOS used in your
motherboard manual, the parameter is 667 MHz, or 1/2 of a FSB speed of 1333
MHz. This implies DDR-2 memory running with a clock of 333 MHz and that is
clocked at 2 X 333 MHz (1 : 1 CPU Clock : Memory Clock ratio) = DDR2-667
MHz/ DDR2 5400 equivalent!
You don't specify WHICH DDR2 memory you have (brand & model number), but it
is likely that it can use a higher than normal voltage (say 2.350 v) and
somewhat longer latencies to operate at DDR2-1066 levels and that it can
ALSO use a more normal voltage (say 1.850 v) and latencies like 4,4,5 when
operated at DDR2-800 levels.
I use Patriot DDR2 8500 / DDR2-1066 SLI memory with a 50% overclocked E4300.
I have operated the memory at equivalent speeds from DDR2-400 to DDR2-1200.
I find that the highest speed (a 1:2 CPU Clock : Memory Clock ratio) and
longer latencies give slightly better performance on SiSoft Sandra2007
benchmarks than DDR2-800 or DDR2-600 [a 1:1 CPU Clock : Memory Clock ratio]
with shorter latencies { ~ 5,8,8 vs. 4,5,5 }).
One thing to keep in mind is that there is as yet no official standard for
DDR2 memory faster than DDR2-800. 'SLI ready' memory is a standards
initiative by nVidia that adds overclocking parameters to Memory module
SPDs. I believe that Intel has a similar initiative.
Bottom line, you can use the full speed of your DDR2 memory to some benefit
(1:1 and 1:2 are not the only ratios usable on most motherboards.) Your
DDR2 8500 memory is likely to outperform any DDR2 6400 with your system, no
matter what the bus speed settings. If you look back a few months in this
newsgroup to March, April, and May you will find a long discussion of how
DDR2 memory relates to bus speeds and clocks for Intel Core2 Duo
motherboards.
So, keep your memory; if you feel the need to return something, I'd suggest
considering swapping for a nVidia 680i SLI chipset motherboard. Or not.
Phil Weldon
"Wizfrog" <googleaccount.DeleteThis@wizfrog.com> wrote in message
news:1193093668.753368.222410@k35g2000prh.googlegroups.com...
| Hello,
|
| Just got a GA-P35C-DS3R with a Q6600 and some DDR2 8500 because the
| box said it was supporting 1333MHz FSB and 1066MHz memory... Well, not
| quite! It does support DDR3 8500 but only DDR2 up to 6400.
|
| So, should I return my DDR2 8500 5-5-5-15 and get a set of DDR2 6400
| cas3 or keep the DDR2 8500 and overclock it from the 800MHz the board
| supports?
|
| I'm not too sure how that works... Can I overclock the memory
| seperately from the CPU? I assume not, it depends on the FSB speed and
| muliplier, right?
|
| So, what's your opinion? Keep PC8500 memory or get lower CAS PC6400?
| >> Stay informed about: DDR2 8500 on overclocked 6400bus?