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Bios dosen't recognize all my RAM (mixed RAM)

Posted on 1998-11-20
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Last Modified: 2013-11-10
I recently added 2 - 32 meg dims of SDRAM  to my existing 2 - 32 meg sims of EDO.

When I boot up the computer the bios shows sdram in rows 0,1 and EDO in rows 2,3 sounds like 4 sims counted right?
But when the ticker counts off the memory check it peaks out at 97 megs and some odd change. So it's missing one sim right?
 
I suspect it would run better if I ran without the EDO, (just 64 megs of SDRAM alone) but if I pull the EDO out the computer beeps once on start-up… and then runs no faster….  

I know this is a BIOS problem
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Question by:SAGWAYMAN
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by:Otta
ID: 1129491
Did the counter pass through 96*1024*1024 (100,663,296) ?

Which BIOS do you have?  AMIBIOS? Award BIOS? Other?
What's the date of the BIOS?
Can you "flash-update" it to a newer level?

(I think that this question has been previously asked;
scan the P.A.Q. files.)
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by:wayneb
ID: 1129492
SAGWAYMAN,

You should not and can not mix sdram and edo, dimms and simms do not match voltage and you can damage the memory if not the motherboard, Your motherboard manual should explain this to you,
dimms use 3.3 volts and simms use 5.0 volts.  Check you motherboard manual or post the make and model of board and I will try to find you a manual if one is available.
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by:arunm
ID: 1129493
Im afraid this is simply not true. Im typing this on a machine that uses a mixture of DIMMS and EDO SIMMS. The memory banks are supplied with different voltages, the fact you have a mixture makes no difference at all.
 
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by:wayneb
ID: 1129494
This is not supported by many many motherboards, including asus and tyan and abit just to name a few. It is not with in the hardware spec to do so. Read up on your hardware.
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by:wayneb
ID: 1129495
Some people claim it's feasible to mix 3V DIMM modules with 5V SIMM modules on a mainboard. However, we do not recommend to use both kinds of modules on a mainboard for the reasons below:  
 
 As the semiconductor process advances, the thickness of gate oxide has become thinner and thinner, 5V I/O may cause the 3V DIMM to degrade. This degradation will change the CMOS properties, especially the CMOS threshold voltage, and ultimately damaging the gate oxide. This means the DIMM modules may fail (burn out) after a period of time due to the gradual degradation process. Exact duration can not be determined, because it also depend on individual semiconductor vendors on the semiconductor processes used for their products.
By inserting a serial resistor between 5V DRAM and 3V DRAM can not solve the problem, since it's the high voltage not the current that will damage the gate oxide.  
 
 5V SIMM I/O data pin will drive 5V signal to 3V data bus. This 5V signal goes through the protection diode to the 3V DIMM power plane and causes the possible IC latch-up effect to occur. To test for the IC latch-up effect is easy, you only need to drive a 5V line into the data line of a 3V DIMM module. If it fails the test, it shows the latch-up effect has occured. However, the latch-up effect may not show up all the time because the signal may not be high enough to go over the threshold every time.
Technology used in the process of producing the DRAM plays an important role also. NMOS process or CMOS process with dual N channel for I/O pin can avoid this effect.
 
Most of the DRAM vendors do not guarantee and will not recommend to mix 5V SIMM and 3V DIMM, because it will decrease the 3V DIMM module life cycle. To protect yourself and your possession please make your right choice and using the right way to protect your system.
If you really want to use 5V SIMMs and 3V DIMMs together, please contact your DRAM vendor to confirm with the 3V DIMM module chips you are using, do not have the above problem issues. However after the confirmation, you can mix 5V SIMMs and 3V DIMMs on ASUS TX97 series mainboards as other mainboard manufactures do.

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by:JBURGHARDT
ID: 1129496
There is jumper on most motherboards that will set voltage to 3.3V SDRAM And RAM will at 5V if you use SDRAM at 5v you will kill SDRAM very fast. SAGWAYMAN your problem is caused by way you put your ram you can only have only two sdrams
at one time or four EDO ram or one bank (two EDO ram) and one SDRAM at time
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by:SAGWAYMAN
ID: 1129497
OK folks, My thanks to everyone who commented. I want to respond to all valid points individually beginning with the proposed answer.
Wayneb: The reason I'm rejecting your answer, (for now), is that it basically dose little more than suggest I check the motherboard manual as opposed to outlining a specific fix action. Which is partially MY fault. It's early in the process here and I've yet to cough up all the necessary details for you to be able to do that.
I surf mostly from WORK while the computer in QUESTION is AT HOME, which makes for sometimes a slow turn-around on checking out suggestions and answering specific questions.
   I suspect you are essentially right about (not) mixing EDO and SDRAM. But I have thoroughly checked out the quite decent, (looking), motherboard manual and it appears to say you CAN (mix RAM types). My apologies, I meant to bring the manual with me tonight but failed in that so I can't give you the exact quote.
The computers behavior (mostly) supports that too. The first thing I did was pop the SDRAM DIMMS into their appointed slots/rows, and booted up the computer all fat dumb and happy. No BIOS changes made by me, no 'auto-detect' nothin' was seen. No beeps, no complaints of any kinds. The only catch was the RAM counter stopped at 98mgs, (prior to which the BIOS set-up displays EDO in ROWS 2,3 and SDRAM in ROWS 0,1) and once windows finishes loading their appears to be no noticeable  improvement in performance.  
   The next thing I did was yank OUT the two EDO dimms. Which caused one or two beeps upon start-up, but no halt, the counter ran off the correct 64 mgs and right on into Windows (98), with, again no noticeable improvement in performance.

WAYNEB: I'm going to open up the question for further discussion, but early exit polls show you with a substantial lead for getting the credit on this one. (see below response to your earlier comment)  

OTTA: The BIOS, I believe, (again the computers not in front of me) is an AMIBOIS BY Award. Date: 95.
It was flash updated not long ago but I've done a "format-C:-Re-install-all" since then. Do I need to do it again?  
   *Again my apologies for not having specific BIOS / Motherboard information for you ALL tonight, I will fire that off for you ALL as soon as I get home this morning, (about 8 hours from this posting).*  
 OTTA: The RAM check runs without a hitch from 0 to 979??K,  (96 mgs = 3, 32mg sim/dims + 2 on the Motherboard) (which is only 3 out of the 4 dim/sims which the BIOS set-up has already confessed to recognizing.!(?) *mifffffff!*)  
   The problem with scanning the P.A.Q. files is you usually have to cough up the POINTS BEFORE you know whether the answer's going to in fact SOLVE your specific dilemma.

ARUNM: Your point has already been covered above. You're right. BUT, I suspect this is NOT true for ALL motherboards. For yours and mine, it is, (appears to be?), true.  
I have a question for you.  How much of each (EDO & SDRAM) are you running and DID YOU perform the upgrade yourself? If so what if any changes did you make to the BOIS set-up?

WAYNEB: (AGAIN): WOW!. EXCELLENT comments supporting your contention in opposition of the mixing of RAM types. Wadda-U some kina ENGINEER?!? GEEEZE!  In light of these comments I'm going to immediately pull the EDO SIMMS OUT until I can find out more about this. I already suspect the computer should perform better with just the 10ns DIMMS and without, the 60ns SIMMS. The mere possibility I could be damaging my superior, expensive new SDRAM is more than enough to tip the scales.  64mgs is plenty.  The start-up "BEEP" is a minor-by-comparison hitch. I'd rather deal with that for now.
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by:SAGWAYMAN
ID: 1129498
JBURGHARDT: We may, I suspect be losing something in the translation here, but,
Perhaps I've misunderstood but. My response is,
I have 4, 72 pin (EDO) rows, there is one 32mg SIMM in each of the first 2 rows. (total 64mg)
I have 2, 168pin (SDRAM) rows, I put one standard 168 pin 32mg DIMM in each of those. (total 64mg)
And the BIOS sucked it up like candy to a baby.  I STRONGLY doubt it's chip/row configuration problem.

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Expert Comment

by:chris_jones
ID: 1129499
Read The Manual.. The motherboard manual should tell you how to set it up with SDRAM and SIMM'S. It will tell you where to put them and if it will work.
Please read the book before you post.
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by:SAGWAYMAN
ID: 1129500
Chris Jones: Dude, I appreciate the input BUT, Read the QUESTION & Full History before YOU post! I read the book THROUGHLY before I ever opened the package the RAM CAME IN... OK?
Now,
For Wayneb and the rest, here’s the missing INFO.

It’s an American Mega Trends AMIBIOS, dated 95.
Also "TVD0220B" comes up with that same screen.
The mother board is an: 8500TVD, Pentium VX System Board.

Now for the bad news. As soon I got home this morning, took out the EDO before doing anything else, but it was too late. One of the DIMMs was apparently already fried (which also explains the missing 32 mg in the count-off check), and it beeped up a storm (not halting however), until I got the correct, remaining single still good DIMM in the correct row. Now it’s happy again. But I’m down to just 32mgs.
RAM BIOS OPTIONS include:

SDRAM CAS# latency: 3,  or 2
SDRAM RAS# Timing: 3:5:8 ,  or 3:4:7

Options exist for EDO Read burst and Write burst.

If anyone has any ideas on this I’ll be glad to give them a try.
I messed around with these a bit this morning with no obvious effects

I’m not sure now if one of my DIMMs might not have been defective to begin with. THE answer, for now, appears to be,  put the right chips, (that aren’t defective) in the right rows, (which you can’t miss because there’s only 2- 128 pin rows) and it works fine all by itself. No BIOS changes needed, no motherboard straps. and my advice is, regardless what the motherboard book says, don't mix EDO and SDRAM.
If you, Wayneb, please would go ahead and re-submit/re-phrase it his answer I’ll accept it now.
One final, probably stupid, question I now have a free 128 pin slot. Can I put something bigger than a 32mg in it without also having to change out/(give up) the 32mg DIMM already residing in the first sloT?

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wayneb earned 100 total points
ID: 1129501
I am sorry to hear of your memory being damaged,
Mixing simms and dimms can damage the memory and is not supported by many motherboard manufactures, the link below has a the manual for your board and according to it dimms must by of like kind, you can add a second 32 for a total of 64 but I would not try to add a 64 with the 32 as the manual does not support this, it may or may not work.

I am glad I could help.

http://biostar-usa.com/pd/tvd/8500tvdsupport.htm

If you need more then let me know.
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by:wayneb
ID: 1129502
I was wrong you can go with a 64 meg dimm and a 32 dimm for a total of 96 megs and you will not have problems, but make sure they are both 15ns 3.3 volt unbuffered dimms and try to match the manufacture of the memory if possible.
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by:SAGWAYMAN
ID: 1129503
Wayneb: Is SDRAM also refered to as "FAST PAGE" RAM?  What my MB manual says is I can mix Fast Page and EDO... or something like that...  I DO HAVE a motherboard manual, but I'm not happy with the way in which certian areas are covered SO I WILL be happy to check-out that manual-LINK you provided. Thanks for that. Thanks also for the secondary answer on the 64mg + 32mg dimm question. thats good news.  Another good rap! I LOVE THIS SITE! Thanks all!

Wayneb: if the question is now locked you may respond directly if you like to:
dsmall@cibernet.it
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by:arunm
ID: 1129504
Hi, I did the installation myself. It was just a question of plugging it in. My sys config is 2 x 32 SRAM DIMMS + 2 x 16 EDO SIMMS I have a Abit TX5 motherboard. I have also seen this being done on a TX-PRO
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by:Otta
ID: 1129505
> Is SDRAM also refered to as "FAST PAGE" RAM?

No.

> What my MB manual says is I can mix Fast Page and EDO.

These are 2 variants of 72-pin SIMMs.
See: http://WWW.TomsHardWare.Com
and read the tutorial about RAM.
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by:SAGWAYMAN
ID: 1129506
Wayneb,
  OK, I've bought a new 64m sdram dimm. but I can only get 16m of it recognized. (48m total) I have a 32m in one (128pin)bank and the new 64m in my other (128pin) bank. Total 48m. No beeps no errors.
  The GOOD news is I AM finally realizing a NOTICABLE difference in performance over the two 32m SIMMS I WAS running before. 48m SDRAM beats 64m EDO. Meanwhile however, I'm still MISSING 48 megs off that 64m DIMM.
  I've tried swapping banks, makes no difference which one is first or last, 48m is all I get. I've played with the BIOS SDRAM "Latency" and SDRAM Timing settings, (again), no apparent effect there either way.
  Worth noting is the new 64m DIMM dose not fly by itself. The 32 however DOES.
  Based on your previous advice & councel, my SIMM banks are left empty. However, upon close examination of the below support HTML YOU sent me:

http://biostar-usa.com/pd/tvd/8500tvdsupport.htm

.unless I'm misunderstanding, (possible), it is saying that for my 64m DIMM to be (fully?) recognized, I MUST have SIMMS WITH the DIMMS(?) yes? no?  

If I had a bad 64m SIMM wouldn't the parity check bitch? It did when I had a (known) bad 32mg DIMM (with or without the other good 32m dimm)...

The other possibility is DIMM type mismatch. I confess I've not been to PNY's "Web wizzard" to determine exactly what I should be using.
The 64 is "TSOP"/64814ASEM-CS (on the box) w/NEC chips
The 32 is  S472M 1D "Cubig" (on the DIMM) w/SIEMENS chips

both PNY.

What can you suggest?

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