Performance problems with dual channel DDR memory

[fedora at geniushealth.com]

Has anyone experienced performance problems when using dual channel DDR 
memory?

We are trialling an Intel 915 GAGL motherboard, using two sticks of 512 
DDR memory, arranged as dual channel memory. Performance drops by 2 to 5 
fold slower when both banks of RAM are installed. When one bank is 
removed, performance raises back to an acceptable level.

Are there any known problems with RedHat Fedora and dual channel memory? 
Are there issues in the kernel / patches supplied, that makes the system 
non-performant when using dual-channel memory? (Possibly also linked 
with a hyper-threading P4 CPU?)

Has anyone else got acceptable performance from using dual channel 
memory with Linux on Fedora? (Either an alternative AMD based system, or 
other?) We'd be very interested to hear.

Our test system
   Motherboard:   Intel 915 GAGL
   CPU: P4 3GHz with hyperthreading
   RAM: 2 x 512Mb DDR (and 1x512Mb for non-dual channel tests)
   OS: Linux Redhat Fedora Core 3
   Kernel: 2.6.9-1.667smp (standard kernel supplied by Fedora Core 3 
install).

Many thanks in advance for any advice / suggestions anyone can offer.

-- 
Regards,

Andrew Mc.Ghee
GeniusHealth Ltd.
Web: http://www.geniushealth.com/

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