Several RAM and FSB Questions

[February]

Hi every one, I have been wondering something, I have a motherboard with
1600 MHz FSB support. My current cpu is a 1333 MHz one, and my rams are
DDR-2 667, which means 1333 mhz. So my FSBRAM ratio is 1:1.

P.SO.: I do not over clock my system.

The questions I have are these:

Since my CPU is 1333, if I install DDR-2 800 rams, my ratio will be 5:4 or
something like that.

1. Will my rams slow down to the FSB of the CPU?

2. If yes, what is the point in installing faster rams if they are slowing
down to the FSB of the CPU?

3. If there is a benefit, what is it?

4. If rams are faster, do they somehow increase the performance of the
graphics cards? (For, both ATI and NVIDIA make use of the system ram Hyper
Memory and Turbo Cache)

5. Wouldn't it be effected by CPU's FSB? Lets say you have a DDR-4 graphics
card, and your rams are DDR-2 800, rams are slower than the card, and CPU is
slower than both of them.

If somebody can answer these I will appreciate a lot. I could not find any
satisfactory answers so far.

Thanks in advance.

 

[Colin Barnhorst]

Stay with 667. Too many users are reporting that their systems will not
boot when the mobo is fully populated with 800 ram. The issue most often
arises with mobos that use nVidia chipsets. Investigate via the forum for
your mobo on the manufacturer's website. A lot of these chipsets use a
memory controller that does 32bit DMA even when running an x64 OS and the
load on the memory controller seems to be too much.

 

[Paul Shapiro]

I have a 1333 MHz FSB cpu with 8GB of DDR2-800 ram. As Colin described, I
had some instability with the ram at 800 MHz, so I dropped the ram to 667MHz
in the bios. I did some very minor benchmarking under both conditions, and
memory throughput was not significantly impacted by lowering the ram speed.
I'm guessing the synchronized access compensated for the slower speed. I am
also not an overclocker, so I don't care about the last 1% of speed.
Stability is my prime concern.

If I was buying again, I might still buy 800 MHz ram because a) maybe it's
more stable with 4 dimms at 667 than memory only rated for 667, and b) if
you upgrade to a 1600 MHz FSB cpu, you might care more about running the ram
at 800. Pricing wasn't drastically different for 667 vs. 800.