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TWIN2X4096-8500C5 & Asus P5N-E SLI


anidem1225

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Greetings,

 

I had two sticks of Corsair XMS2 TwinX DDR2 (2x1GB) rated at 800 MHz and I just upgraded to two sticks of Corsair XMS2 TwinX DDR 2x2GB (TWIN2X4096-8500C5), which are rated at 1066 MHz.

 

When I installed the memory I immediately changed the clock rate of the RAM from the previous 800 MHz to a 1:1 linked speed of 1066/1066 for both the RAM and the FSB since the RAM is now rated at that speed.

 

However, I started to notice some issues when I booted into the operating system (some general instability). I ran Memtest86+ and encountered several errors. I ran at 5-5-5-15, and then the AUTO timing (5-7-7 I believe, which is loose) and the errors persisted.

 

I changed the speed of the RAM to AUTO and it defaulted back to 800 MHz for RAM, with a FSB still at 1066 MHz. Memtest86+ tests afterwards were successful with no errors.

 

My question is why can't I run the RAM at the same speed as the FSB, even though this new Corsair RAM is rated for 1066 MHz operation, without any errors? I applied a BIOS update to my motherboard as well as I feared that it was a much older BIOS, but that had no effect.

 

Any advice or guidance would be appreciated.

 

Thanks!

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Ok so all the RAM tests passed.

 

The only other question I have is running in LINKED and SYNC mode when I boot into Windows and run CPU-Z it shows that the DRAM Frequency is 266 MHz. Does that sound right? I'm assuming if it is right with DDR2 it's basically 266x4 = 1066 which is the correct speed this PC8500 RAM should be running at with a FSB of 1066 MHz?

 

With LINKED and SYNC mode in the BIOS it shows it as 533 MHz in the BIOS and during POST.

 

Thanks!

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Ok so all the RAM tests passed.

 

The only other question I have is running in LINKED and SYNC mode when I boot into Windows and run CPU-Z it shows that the DRAM Frequency is 266 MHz. Does that sound right? I'm assuming if it is right with DDR2 it's basically 266x4 = 1066 which is the correct speed this PC8500 RAM should be running at with a FSB of 1066 MHz?

Yes, you are correct.

Download CPU-z from
.

Look to the Memory tab and if you see 533Mhz then you are running in DDR 533 X 2 = 1066Mhz.

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Well that's the thing, CPU-Z shows the DRAM Frequency as 266 MHz.

 

It makes sense to me to have the setting at LINKED > SYNC in the BIOS, and have it listed as 533 MHz RAM speed as it doubles to 1066 MHz (versus before where I had it to LINKED 1:1 1066/1066 for both), however, because CPU-Z is only showing 266 MHz and not 533 MHz I wonder if I'm somehow missing something.

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Ok I definitely think that I am inadvertently underclocking my memory on this motherboard by selecting LINKED and SYNC for RAM clock settings.

 

CPU-Z, Everest, and SIW all are showing 266 MHz x 2 (DDR) = 533 MHz memory speed. I believe for this motherboard it should be at least 400 MHz x 2, if not 533 MHz x 2 (1066) which is what I'm trying to get it.

 

I've set the RAM clock back to 1066 MHz in the BIOS, and it shows both the actual FSB speed after QDR, and actual memory speed after DDR both at 1066 MHz. I read in another thread that I should disable USB legacy mode when running memory tests so I am trying to run the memory tests again with that disabled to see what happens.

 

Also I am running Rev. 1301 (10/08) of the P5N-E SLI BIOS. I am also running the RAM with 2.1V at these speeds.

 

Thanks!

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Sorry for all the back to back posts here. Memory tests failed again unfortunately at 1066 MHz with USB Legacy support disabled. I'm not sure if I am doing something wrong in the BIOS, or if there is a technical limitation here.

 

I am back to 800 MHz for the memory speed and I'm running tests again to see what the results are.

 

Based on previous results I'm sure 800 MHz will be fine, but does anyone have an idea why I can't do 1066 MHz?

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Try setting tRFC to 60, NB Core Voltage to 1.45v and retest. That's a poor board for a 1:2 DRAM ratio though. You want to run the DRAM twice as fast as the CPU. The CPU is 266Mhz (Quad Pumped) and the DRAM is 533Mhz (Double Pumped). If you had a 333Mhz FSB CPU, it would be an easier match for that board.

 

My advice. Set to 800Mhz and set the DRAM to 4-4-4-12 and Memtest. The difference between 1066Mhz and 5-5-5-15 vs 800Mhz and 4-4-4-12 is minimal.

 

The only other choice you have is to overclock the CPU and gain some bandwidth that way.

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Try setting tRFC to 60, NB Core Voltage to 1.45v and retest. That's a poor board for a 1:2 DRAM ratio though. You want to run the DRAM twice as fast as the CPU. The CPU is 266Mhz (Quad Pumped) and the DRAM is 533Mhz (Double Pumped). If you had a 333Mhz FSB CPU, it would be an easier match for that board.

 

My advice. Set to 800Mhz and set the DRAM to 4-4-4-12 and Memtest. The difference between 1066Mhz and 5-5-5-15 vs 800Mhz and 4-4-4-12 is minimal.

 

The only other choice you have is to overclock the CPU and gain some bandwidth that way.

 

Thanks for the advice. I think after running tests I can't get it to run at 1066 MHz no matter what, and it is more than likely a limitation with the board itself. I think DDR2-800 is the best that I can get on this board, and I've done a few additional searches to find some other folks in a very similar situation.

 

I set it to 800 MHz w/4-4-4-12 timings and it runs solid with Memtest86+, and in general afterwards, so I'll be good with this until a platform change / rebuild later on down the road.

 

Thanks!

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  • 1 month later...
With that CPU yes you will have to set the memory at DDR800.

 

CPU or MOBO? I think it is more of an issue with MOBO. If CPU then what CPU will allow that with the same MOBO.

 

I checked on the corsair mem configurator before ordering this memory and hoping to run at 1066MHz - but can't so far.

 

I just checked (via the link for dominator timing above) on the memory and found out that this memory rated at 1066MHz was only tested at 800MHz?!! What is that?:eek:

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