Lots of Memtest86+ errors when 4 modules fitted.

[chrestomanci]

Hi

I have two Corsair XMMS 2 DDR-2 800 4Gb Kits. Each contains two 2Gb Modules. My System has a Gigabyte motherboard with a G33 chipset. It says that it supports up to 8Gb of RAM. (See specs under my system left)

If I fit either kit leaving the other slots empty, and run memtest, no errors are reported. If I fit both, so the total is 8Gb and all the slots are populated, then test 6 in memtest86+ (version 2.11) reports loads of errors.

I have tried putting a single kit different slots, and it makes no difference, there does not appear to be a problem with the slots.

I have tried increasing the voltage on the memory (from 1.8v to 2.0v, and it reduces the number of errors, but they don't go away.

I have flashed by board with the latest BIOS version, and chosen the 'failsafe defaults' option.

Any ideas ?

[Yellowbeard]

With the board and chipset you have, you will most likely need to run the memory at DDR667 due to the limits of the chipset.

[Barney]

try upping the northbridge voltage as that can add stability when all slots are full

[Main]

I'd say do as Yellowbeard says, I've seen this sort of trouble first hand with an A64 chip (running 2Gb DDR400 on one channel of a Newcastle chip) - if you push memory controller too far it will produce a lot of errors and only calm down when you reduce the frequency or the amount of memory.

Sadly few manufacturers seem to document memory controller limitations like this these days

[Yellowbeard]

I'd say do as Yellowbeard says, I've seen this sort of trouble first hand with an A64 chip (running 2Gb DDR400 on one channel of a Newcastle chip) - if you push memory controller too far it will produce a lot of errors and only calm down when you reduce the frequency or the amount of memory.

Sadly few manufacturers seem to document memory controller limitations like this these days

It's also entirely possible that a system using a G33 chipset may not be OCing friendly and offer the option in the BIOS to up the MCH voltage. It may and it may be fine to do it. But, based on the board, for stability I'd suggest running at DDR667 at the stock voltages. G33 in general is not an OCing friendly chipset.

[AD-15]

I had massive problems with this a while back, except I was using a P35 chipset. Very few boards seem to like 4 RAM modules.

I was advised to simply run my 1066 memory at 800MHz. If lowering the clock as suggested doesn't completely fix the problem, try upping the MCH voltages too (slowly; raise it by one notch, and test it, repeat etc..).

I would use another utility too such as Orthos or Intelburn test to check for instability. When I had problems, the system would fail these tests, but no errors were returned in memtest.

[chrestomanci]

It's also entirely possible that a system using a G33 chipset may not be OCing friendly and offer the option in the BIOS to up the MCH voltage. It may and it may be fine to do it. But, based on the board, for stability I'd suggest running at DDR667 at the stock voltages. G33 in general is not an OCing friendly chipset.

As it happens my board is fairly OC friendly, and it does allow me to up the voltage on the memory or northbridge by up to 0.4v. I tried increasing the memory voltage by 0.2v, and it reduced the number of errors from hundreds down to about 20. I did not want to increase it any higher because the cooling in my case is not that great.

I also tried increasing the voltage on the northbridge, but that actually increased the number of errors.

I will try reducing the clock rate on the memory to DDR667, though I think that might be counter productive, as it would slow my system down more than the benefit I might get from the extra RAM.

[Yellowbeard]

You'll probably never notice the difference between 667 and 800 unless you are interested in synthetic benchmarks. You won't be slowing the CPU so you won't see much difference in any case.

If you really need 800, try +.3v on the memory controller (not the memory of course). Just touch the memory controller heat sink and see if it is uncomfortable to the touch. If it is, you may either have to compromise on the frequency or improve your cooling.

[chrestomanci]

You'll probably never notice the difference between 667 and 800 unless you are interested in synthetic benchmarks. You won't be slowing the CPU so you won't see much difference in any case.

Hmm. I will remember that quote next time I see some stupidly fast corsair memory on sale with an equally insane price.

I reduced the speed of memory down to 667, and ran mem test overnight without errors, Since then I have been running my normal operating system without any unexpected issues, or noticeable performance slowdowns.

Thanks for your help.