Radified User's Guide for the Asus CUSL2

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Post from Mushkin Tech Support
I have permission from Bill Mushkin to post these. 

Copy-n-paste here:

The reason your motherboard is reporting the REV 1.5 module as 3-3-3 is because we program the SPD's for all of our CAS2 modules to run at CAS3 by default when the memory timings in the BIOS are set to automatic. We do this because there are a lot of other BIOS settings that can interfere with SDRAM running successfully at CAS2.

If we didn't set the SPD to default to CAS3 we could be inundated with calls because it is harder for our less technical customers to get there motherboards to run as stable at CAS2 than it is when memory is run at CAS3. This could result in increased prices because of the cost of adding staff to help with the increased amount phone calls, and possibly a temporary decrease in customer service standards. If the customer doesn't know how to manually set the BIOS timings, then we think it's best for them to temporarily run there computer at more conservative settings until they become familiar with there motherboards BIOS and there computers stability. This is because the amount of frustration caused by the possibility of having an unstable computer far outweighs any performance difference.

For customers who aren't familiar with there motherboards BIOS, I would suggest the following links:

(WinDrivers BIOS Center)
(Adrian Rojak Pot's BIOS Optimization Guide)
(BIOS Survival Guide)
(BIOS Tweak Guide)

I just want to make it clear that we are not selling modules advertised as CAS 2 that only work at CAS 3. Our CAS 2 modules can be run at CAS 2 but they have to be setup to do so manually through the BIOS. In some motherboards setting the CAS timing to 2 when the modules SPD is programmed for CAS 3 will result in a warning message at bootup that says "SPD settings recommend CAS 3". This will not affect stability or performance and can be safely ignored. And having to set the memory timings manually won't detrimentally affect performance either.

The REV 1.5 modules have been tested to be compatible with the ASUS CUSL2. Unofficially, I have gotten three REV 1.5 at a time to work at 2-2-2 on the ASUS CUSL2. But for anyone looking for more than 256MB, I would suggest our 256MB REV2 modules as Intel doesn't support running all three DIMM slots at 133MHz. There are a few reasons that the REV 1.5 might not be working but lets start by double checking your BIOS settings.

Under the 'ADVANCED MENU' choose 'CHIP CONFIGURATION' and set:
* SDRAM Timing: [User Define]
* SDRAM CAS Latency: [2T]
* SDRAM RAS to CAS Delay: [2T]
* SDRAM RAS Precharge Time: [2T]
* SDRAM Cycle time: [6T,8T] or [7T,9T] - Depending on which BIOS version you have. After you verify that your system is stable try [5,7], but that may or may not be stable.
* SDRAM Page Closing Policy: [All Banks] - After you verify your computer as stable, move to [One Bank]. This setting will only slightly affect real world video performance in 3D games, although you can ignore this setting if you are only using an external video card.
* Command Per Cycle: Disabled - After you verify your computer as stable, move to [Enabled]. This setting will only slightly affect real world video performance in 3D games, although you can ignore this setting if you are only using an external video card.
* SDRAM Data Driving Mode: [Normal] - Change to [Strong] if you have instability problems, especially if you have multiple memory modules installed. If it is set to [Strong], and you are having problems with one or multiple memory modules, change this setting to [Normal]

Also, make sure that the I/O voltage jumper on your motherboard is set at its default of 3.4V. If none of this helps, you may want to try a lower or slightly higher voltage.


Tech Support
Mushkin, Inc.

Here's another post from Mushkin sppt:

The i815(e) chipset based motherboards only officially support "a maximum of 2 double sided or 3 single sided DIMMs when the SDRAM interface is operating at 133MHz. Upon detection that additional rows are populated beyond these configurations, the BIOS must downshift the SDRAM clocks to 100MHz through a 2-wire interface of the system clock generator.". This is quoted from page 18 of the Intel i815 chipset datasheet available here (PDF).

So supposedly you can only use two 128MB REV 2 modules at a time without the motherboard automatically reverting to 100MHz. However in my experience, motherboard manufacturers aren't following that rule of reverting to 100MHz, and you can install 3 double sided DIMMs. But don't take my word for it, I would suggest following Intels suggestion even though some people may notice no ill affects. 

So I would suggest avoiding three 128MB REV 2 modules and would instead suggest getting 128MB REV 3 modules since they are single sided and allow you to install 3 modules while still following what Intel officially supports. Or you could get two 256MB REV 2 modules which are double sided. The 256MB REV 2 modules will allow you to achieve the maximum amount of memory that the i815 chipset supports, 512MB. As opposed to the REV 3 128MB modules, where you'd be limited to 384MB.


Note that Mushkin now sells 256MB high-density sticks here, where it says, "This module uses high density IBM chips to create a single sided 256mb module. It is perfectly suited for users of the Intel i815E chip set which puts a limitation on the number of "banks" or "sides" of memory the system can use." 

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