Problems with memory on GA K8N PRO-SLI

[bibanu]

I am sorry for the long lines but i wanted to give all the details

Untill 2 days ago I had 2 modules of 512mb of ram from Kingmax(ddr400
@2.5-4-4-8). I bought 2 more modules from Kingston(ddr400@2.5-3-3-8)
because I could not find Kingmax memory . I put the memory in the slots, booted the PC and the memory was recognized fine but when I used Cpu-z and PcWizard2006 to check my memory I saw that the frequency and timings had changed as well as the FSBRAM. I will now explain.
The memory did not worked at 200mhz with 2.5-4-4-8 timings but at160.8mhzwith 2.5-3-3-7 timings.
At first I was thinking that the memory is the culprit but then I tried different settings in the slots and now I think that the motherboard is the problem :idea: . These are the settings that I tried:
1.only the 2 modules from Kingmax worked at 200mhz@2.5-4-4-8
2.only the 2 modules from Kingston worked at 200mhz@2.5-3-3-8
3.one module from Kingmax and one from Kingston worked at200mhz@2.5 -4-4-8
4.the problem was when I put all 4 modules. Memory only worked at160.8
mhz@2.5-3-3-7. I tried all combinations in the memory slots but nothing
5.the "Memory" tab in Cpu-Z shows Fsbram Cpu/12 only with 1gb of ram (from either brand or combined), but with all 4 modules shows Cpu/15
6.I also run a memory benchmark with PcWizard2006 and the memory bandwidht with only 2 modules( from either brand or combined) working at 200mhz@2.5-4-4-8 timings was 6432mb/s but with all 4 modules working at 160.8mhz@2.5-3-3-7 the bandwidht dropped to 5146mb/s

What can I do, because in BIOS there are no available settings for memory excepting those for voltage?

Could the MOBO be broken?

Will a Bios update help?

Is the Mobo unable to handle 2gb of ram because in the manual it states that it can support 4gb of ram ddr400/333/266/200?

Is there any one that has this MOBO and had had a similar problem?

Please help

Thanks

My PC:
MB:GA K8N PRO-SLI revision 1.0, bios version F2
CPU:AMD64skt939 3800+Venice
RAM: 4*512mb ram
VGA: Sapphire x1900gt
HDD: Seagate 80gb sata
PSU:560W Chieftec

 

[bibanu]

Are you using the DIMMS in the correct slot to take advatage of dual channel. If i remeber you ned the first set in slots 1 and 3 and the other set in slots 2 and 4. This may account for the problem. The motherboard is trying to run it in dual channel but in order to do so with miss matched pairs it has to adjust the numbers.

I did that first using the Kingmax memory and then the Kingston memory but still nothing