Jump to content
Corsair Community

2 pairs of TWIN2X2048-8500C5 at 1066?

Sapient Fridge

Recommended Posts

When I built my system I rather unfortunately choose an Asus P5N-T Deluxe, which has caused me endless problems until I got it stable.


I originally bought 4 * 1G PC2-8500 C5 modules and spent months fighting random blue screen at 1066mhz until I realised the memory wanted 2.2V not the 1.85v the motherboard was giving them!


Anyway, a pair of the memory cards died a month or so ago and Scan replaced them with 2 new memory cards. The problem is that although the system works at 800mhz it now refuses to boot at 1066mhz. I asked Scan support for help and they told me to ask here.


The new cards have a different version numbers, the old ones say 1.2 and the new ones say 1.5. Also the new cards say they are 2.1v rather than 2.2v (I've tried changing the voltage to 2.1v without joy.) I've checked that the new cards won't work on their own at 1066mhz either i.e. without the old cards present.


The way I was setting the old memory speed to 1066mhz was by setting the SLI memory mode to "Expert", I haven't tried setting the memory timings by hand yet. Before I try that I just wanted to verify that the memory is actually compatible with my motherboard before I turn it into a doorstop by fiddling with it.


If I do set the timings by hand then is this correct?


FSB Memory clock mode: unlinked

tCL : 5

tRCD : 5

tRP : 5

tRAS : 15

Command per Clock: 2

Link to comment
Share on other sites

The only memory Corsair supports in a four DRAM slot population is their Quad kits. This does not mean two dual kits or even worse two dual kits of different versions will not work together, just that you have no recourse to RMA Corsair if they do not work together. If there are problems with the DRAM modules, they are still supported via lifetime warranty, but that is for physical defects and errors in a two stick kit mode. Matched Quad sets are highly binned modules for a four slot population. The Dual sets are tested as a kit, not a Quad and warranted as a dual kit, not a Quad setup. You need to Memtest them as Kits (2 modules, not as a four DRAM slot population). If they fail as a kit or singly, then you have RMA. Keep in mind that there is no support for mixing and matching different versions of DRAM either since different version are of different fabrications and/or manufacturers. They might work, they might not work, but you have no support if they do not work. Thus you are advised to buy all the DRAM at the same time and in this way be more assured of getting the same versions. If you buy online, be sure to specify same versions of the modules.


You are advised to drop the bandwidth to 800Mhz and raise the NB Voltage +.2v.


Please research this thread:




There is a limitation of the On Motherboard (Intel) memory controller or On CPU (AMD) and a population of all four banks at the full speed of a two bank run. This limitation is across the board with both AMD and Intel chipset based boards, DDR, DDR2 and DDR3.


Keep in mind that often issues can arise in the longer term even though you have shorter term stability. The issues seldom damage the DRAM unless you raise the DRAM voltage too high. They damage the on CPU (AMD) memory controller MCH (INTEL) which has a harder time keeping up with the demands of a four DRAM slot population being run as fast as a two DRAM slot population.

Link to comment
Share on other sites

Thanks for the reply.


I mentioned that I had tried the two new cards on their own as well as at the same time as with the old cards. I previously wrote:


"I've checked that the new cards won't work on their own at 1066mhz either i.e. without the old cards present."


Though from what you wrote it doesn't look like it's worth trying to get all four working at 1066mhz anyway.

Link to comment
Share on other sites


This topic is now archived and is closed to further replies.

  • Create New...