Dual Channel DDR motherboard and rendering w/Blender

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1

I recently had to replace my motherboard (It was an emergency), so I had to get one very similar to what I had, actually from the same manufacture (Gigabyte)

This new MoBo features Dual Channel DDR. You must have equal pairs of memory sticks to use this feature, otherwise you are stuck using Single Channel.

I am not sure what Dual Channel memory is, but my users manual says I can double up the memory to 6.5GB of DDR memory if the memory chips are installed in equal pairs. I have 4 DDR slots.

Does anyone here have this kind of setup on their motherboard? And use it?
Does it help a lot in rendering, if so I may buy some more DDR memory.

2

Dual-channel doubles the theoretical memory bandwidth, not the size of it…though it would help a lot if you tell us what the system actually looks like…
In case of an Athlon-XP, just forget about dual-channel, the FSB of the CPU just doesn’t have the bandwidth to profit from dual-channel, nVidia mainly did it to improve performance of integrated graphics. Otherwise we’re talking a performance difference of less than 5% here, barely enough to measure it.
In case of a Pentium4 with fast FSB it may be a few more percent, but still nothing dramatic. And especially rendering is not very demanding on memory bandwidth.

About getting more memory, it only helps if you need it of course. If you don’t have enough rendering slows down to a crawl and your HD goes crazy. If the scene fits into RAM, it won’t make any difference if you buy 2 more GB (well okay if you have other programs open using large amounts of RAM it may, because they have to be paged first)

3

Hi,

(just two weks ago I had to got through the same problems
and also struggled, when I read about Dual Channel RAM
and such…)

Often confused: DDR2 has nothing to do with Dual Channel.
DDR2 is a “faster version” of DDR.

Duial Channel means: The Northbridge, which together
with the Southbridge builds the chipset of your MoBo,
accesses both banks of DDR (two banks build one pair)
simultanously or in other words 128bit wide accesses are
possible.

Single Channel mode means: When accessing one bank,
the other one is “idle” in that moment.

Dual Channel mode is therefore faster.

If you are not going to overclock your board it is sufficient
to buy a pair of DDR RAM from the same manufacturer
WITH THE SAME TIMINGS!!!
And: If you plan to upgrade your memory later and still
want to use Dual Channel mode insist of buying single
sided ones. The Northbridge will disable Dual Channel
mode if it recognized double sided memory.

Things, which makes RAM accesses faster while still
haveing a stable system:
DONT overclock – it is not that dangerous as often
claimed but it can make a system instable, which results
in random and sudden crashes of the whole system.
More important is to tweak the BIOS setting that way,
that they optimally foit your hardware.

RAMs are often classified by their timings.
You will things like

DDR400 2.5-3-3-8 2T

DDR400 marks the clock speed the northbrige will allowed
to access RAM. Higher number -> higher speed.

Next number is the CAS Latency which marks the time
to wait befor accessing the coloumn of the RAM – RAM
is orgnaized in Rows and coloums.

Next three numbers are other timing values, whic I
found not that important to select speedy RAM.

The last one is the command rate. Smaller number -> higher speed. 1T is good.

Most BIOSs allows to tweak those settings.
If your system hangs due to increasing speed too much
you will have to go back one step. Dont tweak more
than one setting more than one step at once !!!
Otherwise you will go back to start again and insert
another coin to play again :wink:

After haveing found a stable speedy setting boot into
a Knoppix CD and start “memtest” (dont start
memtest from a running system…) and let it do its
work for a night or so. It is just to ensure your
system is stable and to verify transfer rates and
RAM timing settings.

Here you will find the “BIOS Optimization Guide”
http://www.rojakpot.com/freebog.aspx

Have a lot fun!
mcc