Intel BX chipset MOBO memory problem 1

[Jackmetickler]

I have just tried to install a single sided 256MB SDRAM DIMMS onto an ASUS P3B-F MOBO which has the above chipset.
It could only see 128MB of it, even though the manual states it can use 256MB. The memory is right. 168pin unbuffered etc.... although there is no mention of single/double sided. I have checked ASUS/Intel and other Websites with no mention of any problems, but I thought I saw sometime ago an article that stated Intel bx chipset would not see single sided 256mb dimms, only double sided.
I also installing same memory on HP Pavillion 7805 with same problem.... only that can only see 64MB of it !
Have checked out memory on another MOBO and it is fine

Any pointers
Regards
Jackmeticler

 

[ski]

Apparently, the MB's documentation is incorrect.
According to Intel's specs, the 440BX AGPSet will support up to 384MB of SDRAM(100MHz max, single or double-sided)) with 3 DIMM slots, or up to 512MB with 4 slots.
Thus, each module cannot exceed 128MB.

 

[gargouille]

Ski's right:

Just dug out the specs for an old Gateway computer I had.

The chipset will accept single or double side ECC or non-ECC unbuffered SDRAM.

The Taborll 440BX board I had (now in-laws have it) will accept 3 sticks of 16 Mbit X 64(bit) 128 MB, Non-ECC...or 3 sticks of 16 Mbit X 72(bit) 128 MB SDRAM, ECC...MAX.
More than that it will not use/report.

 

[TyrantSSV]

Hi guys!!!

Look here:

http://developer.intel.com/design/chipsets/datashts/29063301.pdf

(Intel® 440BX AGPset: 82443BX Host Bridge/Controller Datasheet)

page iii:

Integrated DRAM controller
— 8 to 512 Mbytes or 1GB (with registered DIMMs)
— Supports up to 4 double-sided DIMMs (8 rows memory)
— 64-bit data interface with ECC support (SDRAM only)
— Unbuffered and Registered SDRAM (Synchronous) DRAM Support (x-1-1-1 access @ 66 MHz, x-1-1-1 access @ 100 MHz)
— Enhanced SDRAM Open Page Architecture Support for 16- and 64-Mbit DRAM devices with 2k, 4k and 8k page sizes (“expedite”) support

I.e. for i440BX total memory amount is 1GB in 4 double-banked DIMMS with 256 MB per DIMM (if REGISTERED DIMMs are used)

 

[ski]

Thanks for the clarification, TyrantSSV.

 

[gargouille]

Lemmeseehere:
Is crow any better with barbecue sauce?
Good heads-up Tyrant....
question is why isn't Jackmetickler's memory working?

 

[Jackmetickler]

Cheers for the great info people.
Not sure exactly where I go from here though.

Have tried various combinations but whatever I use the MOBO can only see 128MB of 256MB single sided mem
I have not invested in any double sided memory as yet as I do not want to waste any more dosh.

Does that mean I can only use 128MB DIMMS
or
Can I use 256MB as long as it is double sided and the total memory does not exceed the MB Parameters

Forgive me if I am being thick here!

Regards
Jackmetickler

 

[ski]

Thanks to TyrantSSV's post, your MB will recognize the full capacity of a 256MB DIMM stick(single or double sided), as long as it's registered.
The ones you're using now are probably unregistered.
Also, registered RAM costs more than unregistered.

 

[gargouille]

Okay, Jason, let's run over to crucial.com...(which I should have done the 1st time...naw don't work for 'em).
Actually, the url is

http://www.crucial.com/index.asp.

There are several ways to find the RAM...but for this trip we'll choose by motherboard...since we know yours is Asus P3B-F...at the middle left of the page...there's a place where you put you mobo mfr.'s name in the box...put Asus in there...and hit go.

Next page at the top left...we have Asus in the box...and it says select your Asus product line...hit the arrow and scroll down 'til we get to P3B-F...and voila! There appears a page of prices and sizes of recommended ram for your motherboard.

While we're here, we'll take Memory 101...and get an explanation of memory terms and what they mean...by clicking on Explanation of memory terms...and a page opens that tells you what registered, ECC and all the terms mean.
Having done that, we go back a page...where all that memory was shown...

But wait, we're not done yet, we're not sure about how much we can put in it...so...if you'll notice at lower left...Motherboard Info: and a link to click to Detailed specs...click that.

And again, the memory scrolls by and at the lower left of the page...there's your motherboard info...and what's supported and not supported. So, let's see, your mobo supports SDR SDRAM only. It doesn't say so on the page we just left, but SDR is single data rate...your motherboard came out before DDR (double data rate) was developed...and if you follow the column down...(stay with me now)it shows you can use (4 banks of 1) 168-pin DIMM Banking. AND, if you follow that column down to the bottom...it says Max Unbuffered SDR SDRAM 1024 MB.

Don't be confused (more than we already are) when it says PC66 and PC100...those were the memory specs current when your motherboard was newly developed. It will take the memory listed in the upper part of the page.

What finally sold me on Crucial is that if you buy this way and it's wrong...(never has happened to me)...you can return it...no charge.

I'll leave it up to you to figure out what kind of memory you bought before this.

 

[gargouille]

As I said in my post, I'll leave it up to Jason to figure out what kind of RAM he purchased...

I would, however, point out that the pages at Crucial I referred to (specifically:

http://www.crucial.com/store/listparts.asp?model=P3B-F&DetailMB=Y&cat=RAM)

indicate this motherboard doesn't support registered RAM.
While the Intel chipset spec may say it does (confirmed it by reading the spec provided by Tyrant)...the info on Crucial's page says otherwise about this board.
So to further advance my spotty understanding of this board I downloaded the manual and it does not specify registered or unregistered.
I would, however, trust the information from Crucial.

 

[TyrantSSV]

Using REGISTERED DIMMs influences on the full memory size, that is 1 GB RAM you can have only without memory controller's lines overloading. REGISTERED modules create much smaller loading and consequently using of them allows to use full capabilities of i440BX in addressing memory. i440BX chipset restrictions on each DIMM slot volume remains - no more than 256 MB per slot when DIMM is double-banked. If the module is single-banked, it should be no more than 128 MB, differently it will be recognized only half. The single-sided or double-sided module - generally it not an attribute of amount of banks and it is only design feature of the module. Depending on used chips the module can contain ICs on two sides and to be single-banked and vice versa - the module can have only one side of chips and to be double-banked.

So, if one 256 MB module is single-banked, for using with i440BX chipset it have to be raplaced with one 256 MB double-banked module or with two 128 MB single-banked.