Divider problems: VS2GBKIT400C3 & Asus A8N-SLI Premium

[KillrBuckeye]

I'll cut right to the chase here. My 2x1GB kit of Corsair Value Select will not run anywhere close to its rated speeds when I set the CPU:Memclock ratio to anything other than 1:1 (DDR400 setting in BIOS). Note: All the dividers worked perfectly when I was running a 2x512MB kit of Corsiar VS. I read somewhere that some of the memory timings are automatically tightened when the memory divider is set lower than 1:1, so I decided to see for myself if this was the case.

 

Here is a screenshot from A64 Tweaker when everything is at stock settings (200x10, DDR400 setting):

http://i7.photobucket.com/albums/y299/KillrBuckeye/Computer/TweakerDefaults.jpg

 

And here is a screenshot when I set the DDR266 (2/3) divider and leave everything else on auto (CPU still at stock speed):

http://i7.photobucket.com/albums/y299/KillrBuckeye/Computer/Tweaker266Divider.jpg

 

The things that have changed are "Write to Read Delay Time" (from 2 at stock settings to 1 with the divider), and the "Read Preamble" (from 5.5ns at stock to 7.0ns with the divider). I'm not sure if this is causing the instability when running a divider, but it sure seems curious. The problem is that these settings are nowhere to be found in my BIOS setup screen.

 

When the memory speed increases slightly to 150-160 MHz, I begin to encounter severe instability. I know it's not my CPU, because it ran up to 2.9 GHz with my 2x512MB kit of Corsair VS. RAMGUY, do you have any insight for this particular issue?

[RAM GUY]

You will need to set the memory frequency and timings manually when over clocking and anything bellow about 180 MHz I would set the timings manually to Cas 2.5-3-3-7 at 2.7 Volts and set them manually at Cas 3-3-3-8 at 200 Mhz and above of the memory frequency. Just remember the memory frequency is a divider off of the CPU Frequency and will over clock the memory by default especially if you do not have the ability to lock the memory frequency.