SDRAM Questions

[Giza]

I want to upgrade the memory on my ASUS motherboard, increasing it from 128 Meg. to 512 Meg. of RAM. I have a choice between PC-100 128 Meg. SDRAM chips with ECC or without. With ECC is currently cheaper by $5 per chip. Is ECC or standard (without ECC) better? The current DIMM I have is without so buying without means I need only 3 DIMMS versus 4 with ECC.

Also, the ASUS manual recommends SPD (serial presence detect) as being the best for stabiity and performance. The dealer did not know whether the DIMMs were SPD or not but he said they were standard chips. Anybody know if that means they have SPD or not?

Finally I assume that since these are standard 3.3 volt DIMMs they are also unbuffered?

Thanks for help on this memory matter in advance. After all, I might "forget" to say thanks later on!


--Giza

 

[shadoe_phantom]

without ECC is better (ecc is the error checking it does) 'cause ECC just slows it down a little. SPD will mean that for you to fully use all slots on your Asus motherboard, the RAM you get must be registered RAM. If your dealer says they are just standard chips, more than likely they are not registered RAM (as registered generally costs about $5-$15 more).
So if you were to buy 3 more sticks & stick them into all your remaining slots, your mobo would probably not recognize them.
Most mobos like that only allow you to use 2 slots of unregestered RAM, however sometimes they will still accept & recognize them.
Ask the dealer if you can test them out & if you can return them in exchange for registered RAM if it doesn't work.

Good luck

 

[Giza]

Thanks shadoe_phantom for the reply. It was an excellent explanation.

The dealer said I can bring in my CPU box and the technicians will test the memory chips on it. That way if they don't work, I can save myself the trouble of purchasing the chips. This place has an exchange only policy.

 

[LTR12101B]

I got very cheap 128 Mb PC133 - and used them in a Gigabyte 7IXE4 (PC100) board - you can often use PC133 satisfatorily at PC100 speed, useful if assholes demand more money for scarce PC100 ram.

3 identical sticks of 128 (not essential, but I like it that way).

they do have SPD, but are not, afaik, "registered" - nope, only "unbufferred" - according to Sisoft Sandra help, modules >= 256Mb need to be REGISTERED.


My board supports ECC, and if i'd had the otpion, I'd have gone for ECC memory - it means immunity to minor memory errors, and detection of larger ones, and greater trust in your system - but ALL the memory needs to be ECC, in order to use it!

PS. do you have FOUR Dimm slots ??

Another point, my 128's use 2 CAS lines each, so diagnostics see 6 x 64Mb banks

 

[auras]

Any PC 100 or PC 133 module will work, and all have SPD. Only the old PC 66 modules was without SPD. A standard SDRAM memory card "side" (each side of a two-sided card is a distinct memory block) have 8 memory chips, and a 9th, EPROM chip, having inscribed the SPD data. At the system start, the BIOS reads the SPD data and makes the appropiate settings for the memory. The ECC (error checking & correction) is not necessary for a home PC (and maybe is not supported by the mainboard). But, be careful, and read the mainboard manual. I don't know what Asus mainboard you have, but many, especially Intel mainboard does support only maximum 4 "sides" of SDRAM (i. e. max. 4 single-sided SDRAM module, or 2 double-sided, or 1 double-sided + 2 single-sided).

 

[Giza]

It's a very pleasant surprise to receive so much knowledgeable info on this subject.

My motherboard is an ASUS P3B-F with 4 DIMM slots. It accepts both single-sided and double-sided DIMMs in any combination. According to the manual, though, if I do not use PC-100 compliant DIMMs, then I must lower by CPU bus frequency from 100 MHz to 66 MHz. I am assuming that at the time the manual was written, PC-133 SDRAMs were not in existence.

Now LTR12101B and auras, you say it's okay to use PC-133s. Can I do that and still leave my bus frequency at 100?

auras, are you absolutely sure all PC 100 and PC 133 modules have SPD? The dealers I talked to did not even know what it was let alone if the SDRAM modules they carried had it. You would think people in the business would know.

I just tried out a PC-100 128 Meg. SDRAM module from Kingston. Picked it up as a test (it's returnable for full refund) on my way home today. Tried installing it into system but my system didn't recognize it, only the original 128 Meg. module installed. While fiddling with it, I noticed that in the BIOs it is set to recognize SDRAM "by SPD." So it makes me wonder about SPD being standard. Anyway, this module I was testing is a high profile one and I had difficulty in getting it to sit tightly and securely into a DIMM slot.

LTR12101B, are you using Sisoft Sandra Pro 2002? I did not find it as informative in giving me info about my installed memory as my ASUS Probe utility. But I will have to check out Sisoft's help modules.

 

[LTR12101B]

Running PC133 DIMMS at PC100 FSB will normally work - it does for me, and 7IXE4 motherboard is actually notorious for being fussy about RAM.

They obviously though "not PC100" meant PC66 when the instructions were written.

The order in which the modules are used can be important - to correctly set timings, I suspect it must see the one with the slowest (CL and other timings) settings first.

Try modules individually and then in reverse order before condemning! Using a matched set avoids this kind of fiddling, assuming the modules ARE basically compatible with the board.


Yup! - FOSI of course!

PS. Use an antistatic strap, or at least touch the PC case before handling - and turn off mains power, as ATX soft-off leaves some voltages still active (5v start supply).

 

[bode]

Quote: to fully use all slots on your Asus motherboard, the RAM you get must be registered.

Never knew this! Is it possible to mix registered and unregistered RAM when using more than two slots?

Thanks

 

[auras]

P3B-F & SDRAM

I downloaded the manual for your P3B-F, and I see, there is an Intel BX440 Slot 1 mainboard. This does not have the four memory row limitation like the i815 mainboards, and you can use PC 100 or PC 133 modules, but no more than 128 MB per row (i. e. you must use 128 MB single-sided or 256 MB double-sided modules). According the manual, it seems the mainboard does not support registered (buffered) DIMMs - but the registered DIMMs are not standard memory cards. The PC 133 modules are working fine at 100 MHz FSB. I have an old P 350 with a Soyo BX440 Slot 1 mainboard, which is equipped with two single-sided 128 MB PC 133 unbuffered DIMM, working on 100 MHz FSB, of course.
About the SPD: the newest SPD-less memory modules I seen, was manufactured in 1998. I have in my house four PCs, and in any moment I can build one more with the components I have. I built "manu propria" a lot of of PCs for my family & friends, but I never seen PC 133 memory without SPD or not working on 100 MHz or 66 MHz FSB. Look at the attachment: there are 2 pictures: a PC 133 module with SPD, and an old PC 66 without SPD. The small chip in the upper right corner of the PC 133 card is the EPROM holding the SPD data. The PC 66 does not have this chip. If the memory is ECC, there are 9, not 8 chips on the card (plus the EPROM). The 9th chip (usually in the middle of the card) is the error checking chip (having the same size as the memory chips, not small like the EPROM). Unfortunately, I had no an ECC module to send you a picture. But the ECC is not necessary, the computer will work with non-ECC memory without any problem.
If you want SiSoft Sandra, go to h**p://www.sisoftware.demon.co.uk/sandra
to get the shareware version. But Sisoft Sandra is a good diagnostic program, giving in many cases very bad advices...
A very good hardware info program can be downloaded from
h**p://hwinfo.com - the DOS version is more powerful - but if you are using WinMe or XP (and FAT32, no NTFS!), you must boot from a DOS 7 (Win98) boot disk (eventually loading only himem.sys and anything else, to keep the DOS memory free). Warning! A no-name ("on-ship-made") memory will not return correct data!
Or, go to zdnet or another software portal and search for the AMI diagnostic program.
And do not believe that the ones who are "in business" are knowing too much about the hardware they are selling...
That's all!

 

[Giza]

Thanks LTR12101B and auras!

From scouting around, the PC133 256 Meg modules are the better value in terms of amount of memory and price. So I'm going to that route first, keeping in mind all the great advice I've received here.

I have to agree with you auras. The ones in the business of selling the hardware are not necessarily in the "knows." The real pain is when you are asking a legitimate question and they are responding as if you are the idiot. Now do they really think people want to buy from someone treating them like that?

 

[auras]

Be sure that the 256 meg modules are DOUBLE-SIDED, otherwise you can have (not nice) surprises. The mainboard supports max. 128 MB per row!
They (the guys who are "in business") are considering you an idiot, because the majority of their customers are real idiots...

 

[Giza]

Thanks for all the advice, everyone. After spending time recovering from system problems and a couple of crashes (had to restore from image backup), I am back on and with a knowledgeable reply from support at ASUS regarding SDRAM. Thought I would share it here with others.

----------------------------------

Dear valued Customer,
Thanks for Contacting ASUSTeK.

1. Since this model can only support PC100 memory, also in theory, pc133 memory is compatible with pc100, but it will only run at 100Mhz,
and maybe some module can't be recognized correctly.
That is to say , you can use PC133 on the MB with fsb 100M , but we can't guarantee the stability.
2. All PC100 and PC133 or uper SDRAMs have the SPD chip.
3. On the MB, each memory socket can support up to max 256MB PC100 SDRAM. So 256MB multiplying the memory socket number is
the max memory that the motherboard can support.
If you use the single bank 256M SDRAM on the MB, it can be detected as 128MB as max; that's the BX chipset's limitation. We suggest
you may use the dual-bank SDRAM on your MB, and then the system can detect them normally.
And sir we must let you know that the win98 only can support 512 MB menory so if you want to use more than 512 Mb you should use the
NT or win 2000 ,winXP.

If you use 256MB DIMM, please use registered DIMM.
If you use 128MB or lower, it doesn't matter to use registered or unregistered DIMM. Generally speaking, 128MB or lower DIMM are
unregistered because they are made by 16** or less chips and don't need register. For 256MB DIMM, the chips number are more than 16;
therefore, this signal must be enhanced by registers. There are usually two registers on registered DIMM.
Due to extra registered process, theoretically, the registered DIMM is slower than unregistered DIMM.
There are some information listed as follows about register DIMM:
1. Registered DIMM is slower than Unregistered DIMM.
2. For 256MB SDRAM, registered DIMM is more stable.
3. Due to BX chipset limitation, you cannot mix "unregistered" SDRAM and "registered" SDRAM on P2B series motherboards.
4. Registered SDRAM is started to support from BIOS 1005 or later.

¡»
Best Regards,
ASUS Customer Service Center Shanghai

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[LTR12101B]

Win98 CAN support more than 512Mb, but a tweak is required:

You must limit the total of:
1. BIOS AGP Aperture size
2. System VCACHE

to 512Mb or less

There are many utilities that will allow you to control VCACHE, and also advice on manual adjustment.