ASUS P5B Deluxe + 4GB TWIN2X2048-8500C5 = Blue Screens?

[GitDat]

I've been running 2GB of the TWIN2X2048-8500C5 with no problems for about a year. As soon as I add an additional 2GB of the same revisioned RAM I start getting blue screens.

 

This is in XP and Vista 64. I even tried enabling/disabling the memory remapping setting in the BIOS and it makes no difference in either OS.

 

I'm running BIOS revision 1216. Intel Q6600.

[DerekT]

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.

 

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 the capabilities of the DRAM since the chipset is now clocked up. Usually when you clock up the FSB and concurrently the Memory Controller Hub (MCH) you need to raise the voltages of the CPU/MCH a bit as well.

 

Lower your DRAM speed to 800Mhz and test for stability.

[GitDat]

I slowed it down to 800MHz and no more blue screens :): Thanks. At least when it runs at the slower speed it tightens the memory timings to 4-4-4-12.

[DerekT]

If you set your memory to 2.1v you might also try setting the timings manually to 4-4-4-10 and test with Memtest. Download memtest from http://www.memtest.org and burn the image to CD. Boot to the CD and see if you can make 4-4-4-10 @ 800Mhz.