[clug] OT: DDR RAM and FSB speed

Darren Freeman daz111 at rsphysse.anu.edu.au
Thu Feb 3 01:33:54 GMT 2005

On Fri, 2005-01-28 at 08:13, Duncan Roe wrote:
> Hi Darren,
> Just checking - are you saying DDR400 & PCI3200 are different?

No they're the same. Only it's PC3200 not PCI3200.

> I was told emphatically by the PC shop that they were the same, but I'm having a
> problem with my dual Opteron - BIOS only sees 3.5G with all 4 sticks in but sees
> 2G with any 2 in. Tech support said to upgrade to latest BIOS which I did, but
> the problem persists.

Perhaps you are running them in 32bit mode? 32bit addressing hits a
limit at 4GB. Leaving room for other memory-mapped peripherals, I can
see why this might happen. But in 64bit mode it shouldn't have this
problem, at least at the CPU level anyway, and I hope they haven't done
anything weird in the motherboard.

I've never touched an SMP machine so I don't know if there are issues
with the two CPUs each controlling two sticks and then having trouble
sharing the memory between them. Or whatever.

> Cheers ... Duncan.

Have fun,

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