Twin2X-6400C4 and Abit IP35-E settings

[Zot1369]

Hello,

 

I recently installed 4 sticks of Twin2X-6400C4 in my IP35-E (Vista Ultimate 64bit) At default settings, CPU-Z tells me I am running at 5-5-5-18. How do I get the advertised 4-4-4-12? When I manually set voltage to 2.1 and timings to 4-4-4-12, memtest fails test #5 - consistently with the same memory locations and error. If I set to defaults, I end up with 5-5-5-18 again. Any suggestions?

 

Thanks,

 

Zot

[DerekT]

The memory controller can not keep up with the extra DRAM at the rated PC6400 (800MHz) speed. You will need to drop the speed of the DRAM from 800Mhz to 667Mhz. If you had purchased 4 X 1024MB of PC8500 (1066Mhz) DRAM, then you would have had to drop to PC6400 (800MHz) 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. If you have a small phone book, then when you go into the index to find the page where you will find the phone number you are doing so at a certain speed due to the pages of the Index. Then you have to drive through the pages to get to the number. Now if your index is twice as large and the pages twice as many, then it takes longer to access the data. Now DRAM has a Strobe and the length of the strobe is how long the rows and columns can be left open before they must be refreshed. There is not enough time for the dram to be refreshed and then accessed with 4GB at the full access speed of the DRAM. The chipsets are optimized for 2GB, not 4GB and for 2 DRAM slots, not 4 DRAM slots populated.

 

You can overclock the FSB (and hence the Memory Controller Hub = MCH) to gain some extra bandwidth, and thus access more of the capabilities of the DRAM since the chipset is now clocked up and running faster chipset <--> DRAM. Usually when you clock up the FSB and concurrently the Memory Controller Hub (MCH) you need to raise the voltages of the CPU/MCH (0.5V) a bit as well.

 

Set to 667Mhz, set your timings and Vdimm. Test with Memtest. Results?

[Zot1369]

Thanks Derek. I had heard with some AMD systems that was the case, but I didn't expect that with this board. I am curious - and I admit I am no expert in this area - why are all 4 stick stable at default values and 5-5-5-18 speeds? I didn't have to change any settings when I first installed the 2nd pair and CPU-Z didn't show any step downs in MHz or timings with the 2nd pair.

 

Based on other things I read, I did decide to up the DDR voltage to 1.9 (2.1 was running TOO hot and may have contributed to the instability I mentioned), and set timings to 4-4-4-12 manually. Stable as rock since then.

 

Thanks for the info though!

[DerekT]

Thanks Derek. I had heard with some AMD systems that was the case, but I didn't expect that with this board. I am curious - and I admit I am no expert in this area - why are all 4 stick stable at default values and 5-5-5-18 speeds? I didn't have to change any settings when I first installed the 2nd pair and CPU-Z didn't show any step downs in MHz or timings with the 2nd pair

 

There are exceptions to any rule. However, all you need to do is search this site, google and any other DRAM/Motherboard site with "4 DRAM Slots Filled Problems" and you will see that there is usually (not always) problems associated with this. This is the case with both AMD and Intel chipset motherboard.

 

Good that you are not one of the many who do experience problems and hopefully you do not find instability in the future. Having to raise the timings is not a bad trade off considering some of the problems I have seen with four DRAM banks populated. I have also seen system maintain stability for some time and then completely error out with physical issues. Hopefully will not be one of those.

 

Do not think that because you were able to do this, that this is not an issue as you would be quite in error. Also, advising people that this is an easy move because you have made it would also be not only in error but you could well find yourself answering questions as to why you advised such a troublesome thing.

 

I personally advise people to purchase 2 X 2048 as now with the price of DRAM dropping, it's a far better choice.

[dguarnaccia]

Raising the Northbridge voltage by +.06 volts seemed to fix my issue. I'm running 4 CM2x1024C4D's on a MSI 965 Platinum, and was getting tons of erros on Test 5 of Memtest. Even with the timings at 5-5-5-18 I was having issues, but incrementing the MCH voltage from 1.24 to 1.30 seems to have fixed the issue for me now.

 

Thanks for the good advice all :):

[DerekT]

You're very welcome...