8GB (4x2GB) DDR2-800 - Downclock or Not?

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I recently purchased two (2) OCZ OCZ2P8004GK DDR2-800 4GB dual-channel kits, and after ensuring that each pair is stable on its own, I am ready to insert all four (4) DIMMs for a total of 8GB. My problem is I am unsure of whether or not I need to downclock to DDR2-667 speeds when populating all of my slots. Take a look at the following post:


DerekT @ Corsair Forums said:
It is advised to drop the bandwidth when populating with four DRAM slots. The memory controller can issue errors.

Please research this thread:

http://www.houseofhelp.com/v3/showt...edictable+results+QUAD2X4096+Gigabyte+X38-DS5

The issue is the memory controller and a population of all four banks at the full speed of a two bank run. This issue is across the board with both Nvidia and Intel chipset based boards.

Keep in mind that often issues arise in the longer term. The issues seldom damage the DRAM. They damage the on motherboard memory controller which has a harder time keeping up with the demands of a four DRAM slot population being run as fast as a two DRAM slot population. Those who want to be secure in their system either purchase a single kit of the DRAM capacity that the four singles have or they move to a higher bandwidth DRAM and drop the bandwidth. I also advise it as I have personally seen the issues that can and often do arise with a four DRAM slot population running at the full speed of a single kit speed.
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Same Person said:
The memory controller can not keep up with the extra DRAM at the rated 8500 speed. You will need to drop the speed of the DRAM from 1066Mhz to 800Mhz. If you had purchased 4 X 1024MB of PC6400 (800Mhz) DRAM, then you would have had to drop to PC5300 (667MHz) DRAM, etc. 2 X 2048 will not issue this problem. This is a problem of all 4 banks being populated.
Think of it this way. A good analogy representing visualization of the above specifications is a passenger truck. Let‟s assume that the maximum hauling capacity of the truck is 8000 pounds representing 8GB of memory. The top speed of the truck is 106.6 mph representing a memory speed of DDR1066. However, this does not mean that the truck can haul 8000 pounds at 106.6mph. The physical limitations are similar for a memory controller as 8GB and 1066 are both tested maximums for this memory controller. When the memory controller speed is increased for overclocking, it simply cannot manage the same amount of memory at that overclocked speed for proper stable communication with the CPU.
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Is downclocking really necessary when all of the DIMM slots are populated, or would running DIMMs at full speed be safe for my hardware? I have research this issue to death without finding a satisfactory answer, and I would greatly appreciate some help. :)
 
To anyone who is just reading this thread, here is a slightly better description of the issue to which I referred in my OP.

DerekT said:
There is a limitation of the On Motherboard (Intel) memory controller or On CPU (AMD) and a population of all four banks at the full speed of a two bank run. This limitation is across the board with both AMD and Intel chipset based boards, DDR, DDR2 and DDR3.

Keep in mind that often issues can arise in the longer term even though you have shorter term stability. The issues seldom damage the DRAM unless you raise the DRAM voltage too high. They damage the on CPU (AMD) memory controller which has a harder time keeping up with the demands of a four DRAM slot population being run as fast as a two DRAM slot population.
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Uh, I run all my memory sticks at 800MHz, and even a bit higher if necessary. I only down clock if additional voltage is required to push the memory further to achieve a higher overclock. (not worth it IMO, since memory is probably the most fragile hardware in a computer box)
 
blade52x said:
Uh, I run all my memory sticks at 800MHz, and even a bit higher if necessary. I only down clock if additional voltage is required to push the memory further to achieve a higher overclock. (not worth it IMO, since memory is probably the most fragile hardware in a computer box)
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^ I think that's it. Memory controllers have rated speeds--if they're not capable of handling memory at their rated speeds we should be bitching at the people doing the advertising.

With that said, 4 sticks generally means more memory being addressed which is an increased workload on the controller. Additional cooling on the NB or CPU (depending on where the controller is) wouldn't hurt.

I'd like to see something definitive though. Everybody says "it stresses the memory controller"--some hard numbers and reasoning (about possible long-term effects running 4 sticks at rated speeds) from an engineer-level brain would be nice.
 
IMO, you should only downclock if you cannot tune the BIOS manually to be stable 4 up at DDR800. It really depends on your individual MOBO due to the variance in any given batch of chipsets/memory controllers. Some will and some won't and the only way to know is to install and test.

As far as running higher voltages or running 4 up as opposed to 2 up, think of it like a car or any piece of equipment or machinery. Placing 2x the load on it will cause it to wear or degrade faster. However, there is no linear chart to gauge exactly how fast this will happen. It may be something like instead of lasting 10 years running 2 modules, it lasts 7 running 4 up.

For example, I have 2 ASUS P4C800 Deluxe MOBOs that have been running OCed and/or 4 modules since 2002 or 2003 when they came out. They are still going strong but, I have also had 2 of them die during that time. The best of the bunch ran a 2.4c at 3.3 pretty much the entire time. The CPU is in another P4C800 now but, that specific board died last year. But, it was obsolete for my uses so the longevity or lack thereof was not an issue.
 
This sounds promising, I am now stuck at 6GB 3x2GB sticks because if I put in a 4th stick I get errors with memtest test #7. I should try the forcing the ram from being DDR800 to DDR 667 and see if I can run with no errors w/ 4x2GB sticks. I know voltage increasing didn't help me at all but I never thought to actually run the RAM at a slower speed.
 
LurkerLito said:
This sounds promising, I am now stuck at 6GB 3x2GB sticks because if I put in a 4th stick I get errors with memtest test #7. I should try the forcing the ram from being DDR800 to DDR 667 and see if I can run with no errors w/ 4x2GB sticks. I know voltage increasing didn't help me at all but I never thought to actually run the RAM at a slower speed.
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What you will be doing is slowing the NB aka memory controller frequency. A memory controller simply cannot run as fast with 4 modules as it can with 2.

Also, are you talking about memory voltages or the memory controller voltage?

AN806 might be helpful: http://www.corsairmemory.com/appnotes/default.aspx
 
Well it didn't work for me. I just tried it earlier, but I still get memory errors when I have 4 sticks of ram. I dropped the speed from standard to as slow as it could go. Looks like I am stuck with 6GB for now. I am thinking it might be a bios problem but since it's an abit motherboard I don't think there will ever be another bios upgrade. I did check each slot and each pair of memory sticks and as long as only 3 slots are used everything works fine.

I adjusted the memory voltages. To just a bit above it's spec but it didn't help. So I just removed one stick and will give up on having 8GB for now.

Thanks for the link though.
 
The ABIT IP-35 series is not great at running 4 modules.

I adjusted the memory voltages. To just a bit above it's spec but it didn't help. So I just removed one stick and will give up on having 8GB for now
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Did you adjust the memory controller voltage or just the memory voltage?
 
I guess it still isn't clear to me.....is this only when overclocking the mobo or other components? I am ready to max out my mobo very soon....don't want to have to downclock. Sounds very misleading from manufacturers if we can't max out capacity at "normal" speeds.
 
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