"Martin" said:
At the bottom of pg 2-11 of the manual it says:
"When all four sockets are populated with 1GB DIMMs (total 4GB) the system
may detect on 3+GB (a little less than 4GB) due to the Southbridge resource
allocation"
So, 2 outstanding questions:
1) Can any identify some 2Gb DIMMs - to realise the 8GB potential?
2) Failing that, I plan to use Crucial 1GB 184pin DIMM PC3200 DDRRAM ECC
Registered CL3.0. Unfortunately it's not on the list of qualified modules.
Has anyone used this module on the sk8v successfully? I can't by Apacer
from normal supplier (
www.dabs.com).
Thanks
Martin
It gets more interesting...
Of all the information I've been able to find, the Kingston site
is the one that thinks DDR400 is limited to two modules.
http://www.ec.kingston.com/ecom/con...sp?SysID=+16777+&distributor=0&submit1=Search
"Comments
KVRxxxx/xxx MODULES MUST BE ORDERED AND INSTALLED IN PAIRS.
KRX3200K2/1G is a kit of two.
KRX3200K2/xx parts have a timing of 3-3-3 (AMD approved)
KRX3200AK2/xx parts have a timing of 2.5-3-3
System Memory Configuration
Standard Memory: 0MB (Removable)
Maximum Memory: 2GB per CPU using 400MHz DDR
8GB using 266MHz or 333MHz DDR
Expansion: 4 Sockets (2 banks of 2)
CPU & ChipSet: AMD Opteron (SledgeHammer) VIA Apollo K8T800 (VT8385)
AMD Athlon 64 FX VIA Apollo K8T800 (VT8385)
Using 266MHz or 333MHz DDR:
Virtually any configuration up to 8GB can be reached using Kingston's
128, 256, 512MB, 1, and 2GB modules IN PAIRS.
Using 400MHz DDR:
Any combination of Kingston's 1 and 2GB kits can be installed to
reach configurations up to 2GB per CPU."
My apologies to Wolfgang. There must be a population rule somewhere
in an AMD document. I've spent a couple of hours trying to find it,
but no luck. I guess the marketing department guides the tech doc
people, on what not to document
Kingston must have obtained
that info from somewhere.
In the AMD datasheet #31412 "AMD Functional Data Sheet 940 pin package",
it says:
* DDR400 supported by Rev C0 and later, Refer to AMD Opteron
Processor Power and Thermal Data Sheet, order# 30417, for silicon
revision determination
For programming information and specific details of the features
listed above, refer to the BIOS and Kernel Developer¹s Guide for
the AMD Athlon 64 and AMD Opteron Processors, order# 26094.
and I'm not able to find anything relevant. Any of the "Motherboard
Design Guides" cannot be found on the AMD site, so maybe those
are NDA only documents or something.
I remember when the K8V came out, there was a table in the 26094
manual, of slot population versus speed for the Athlon64. I made a
posting in which I included a link to the document, but I guess I
threw my copy of version 3.0 of the document away. Later versions
of the document removed that table, so AMD wouldn't have to admit
to the limitations of the Athlon64 S754. I hope the same hasn't
happened to population rules for the FX, if there are any.
From an engineering point of view, having a single slot limit at
DDR400 on a registered memory bus, doesn't make a lot of sense.
That is a very lightly loaded addr/control case.
The following article compares performance with dual DDR333 and
dual DDR400 on the FX, and the results are a mixed bag. There is
something just not right about the Athlon benchmarks, with regard
to memory bandwidth and usage. It is almost as if the core of the
processor is ready to handle a single channel of bandwidth, but
the memory controller is dual channel, like the Nforce2 in a way.
The reason I say this, is there seems to be a disconnect between
the theoretical bandwidth, and how the processor actually uses it.
I first saw some of this, when researching Harlan Stockman's question
about the best processor for his fluid mechanics simulations. One web
site had noted a low measured memory bandwidth, which seemed strange
at the time. Notice, in this article, how sometimes the DDR333
equipped motherboard is faster, and other times the DDR400 motherboard
is faster.
http://www.computerbase.de/artikel/hardware/prozessoren/amd_athlon_64_3000/drucken
The only other way to get an answer to the question, is to find
another manufacturer's version of the SK8V, and get their manual,
and see if they wrote up the memory population rules.
Here is a dual Socket940 board:
http://www.msicomputer.com/product/p_spec.asp?model=K8T_Master2_FAR&class=mb
On the Newegg site, it says in the Detailed Spec section:
- 144-bit DDR at 200, 266, 333MHz, 400MHz.
- Supports DIMM sizes from 64MB (128Mb x 16 DRAMs) to 2GB on each DIMM slot .
- Supports 4 DDR DIMMs upto 8GB (Registered Memory only)
- For Single AMD® Athlon-64 FX 51 series, it will support Registered
Memory up to DDR 400
- For Single or Dual AMD® Opteron Series , it will support Registered
Memory up to DDR 333
and there aren't any caveats about limiting the number of DDR400 DIMMs.
I've looked at some Tyan info, and they don't mention a module limit
either (S2875,S2885). If I look up the MSI Master2-Far on the Kingston
site, it lists the same info as the SK8V. Kingston list similar type
info for the Tyan products.
In any case, according to the Kingston info, it looks like some
DDR333 will work no problem. A 2GB registered DDR333 module:
KVR333X72RC25/2G 2GB 333MHz DDR PC2700 Reg ECC DIMM $742.00
On the Crucial site, they have some PC3200, so you could use this
to test out the Kingston claims if you want. At these dollar figures,
a call to their tech support, to cross check the Kingston claim
would be well worth it.
Crucial CT25672Y40B 2GB PC3200 CAS3 Reg ECC $999
In terms of support for 8GB, there are two "Top of Memory"
registers, one for the area less than 4GB, the other for the
area from 4GB on up. As far as I can tell, this allows for
a gap between 3+GB and 4GB, for PCI address space and AGP
aperture and the like. Access to above 4GB requires the
PAE extension ? For more info, look in #26094.
I wonder if there is a number you can phone at AMD, to
get some answers ?
Paul
