Motherboard Recognizes Half of SDRAM

[JRob]

I'm a newbie here and this is my 1st post, so here goes...

I stumbled on SysOpt Forums with a Google search for info. on my memory upgrade problem. I found this thread http://www.sysopt.com/forum/showthre...hreadid=179781
which discusses what can cause your motherboard to recognize only half of the memory on a stick of RAM.

My PC has a Biostar M6VLQ socket 370 motherboard with Via VT8601T Chipset running with a 1.1Ghz Celeron CPU with 256kb L2 Cache and 100Mhz front side bus. It has two 164 pin DIMM sockets and claims to take up to 1.0 Gb of SDRAM at PC133. I have been running with 256mb of RAM -- two 128mb sticks (one PC100 and one PC133. Both are single sided with 8 chips per side.) I recently installed WinXP Pro with SP2 and it seems to be sluggish. I know that the new operating system is a RAM hog so I decided to upgrade. I bought a 512mb stick of PC133 SDRAM. The RAM was made by TA Memory (Product# 512UNZWM2) and has a lifetime warranty. It is double sided with 8 chips per side. Each chip is marked 64x4SL8BTW. When installed in my PC it only recognizes half (256 of 512) of the RAM. My Biostar MB manual shows both double sided and single sided SDRAM in the installation guide. There is no mention in the manual of limits on RAM chip density.

I have tried a few different settings in the BIOS changing the RAM clock speed or the number of banks but it still only sees 256mb. I have the most current BIOS installed which is available on the Biostar site.

It sounds like the chip density is too high for my Biostar mb. What I don't understand is that no 512mb SDRAM I have seen has more than 16 chips. Doesn't that mean that the chip density must be no less than 64mb? How then is it possible for a 512mb stick of RAM to work in my machine?

I appreciate your help

Jim R

[Sterling_Aug]

It sounds like a trip to crucial.com and a search for your mobo/system will turn up the correct types and sizes of RAM for your system.

[JRob]

Originally posted by Sterling_Aug
It sounds like a trip to crucial.com and a search for your mobo/system will turn up the correct types and sizes of RAM for your system.

@Sterling
Yes, I know Crucial has 512mb PC133 SDRAM for my machine (for $93. ) Which has either 16 chips (dbl. sided) or 8 chips (sngl. sided).
But something does not add up here. If chip density is my problem how does the Crucial SDRAM solve it? Or is chip density NOT the problem?

(BTW I paid only $30 for my new RAM which runs fine at 256MB. The comparable Crucial 256mb RAM is $57.)

[Midknyte]

it's the chip density. you need to get lower density modules.

are you sure that board can take 512MB dimms?

[Ol'Tunzafun]

512MB dimms are all, necessarily, constructed from high density chips. If there are 16 chips on a 512MB dimm then the chips must be 32MB each, or as the chip manufacturers say, 256Mbit. (1MByte = 8Mbits).
The chipset on your board, as you can determine from the chart on the following site, cannot accomodate anything above a density of 128Mbit (16MB) chips.
http://users.erols.com/chare/chipsets.htm
In other words your board cannot fully utilize 512MB dimms and can only accommodate 256MB dimms with 16 chips.

[Ol'Tunzafun]

Hmmm...I guess I should have looked at the chart first. That chipset should be able to utilize 256Mbit chips. This suggests a BIOS update is in order.

[JRob]

Originally posted by Midknyte
it's the chip density. you need to get lower density modules.

are you sure that board can take 512MB dimms?

Thanks for your reply. Am I sure? Well, the specs on the motherboard say it will take up to 1.0Gb of PC133 SDRAM. It only has two sockets for RAM both 164pin DIMMs. And Crucial guarantees their $93, 512mb PC133 SDRAM will work. Those who should know seem to be sure it can take 512mb DIMMs.

What I am trying to understand is what chip density really means. For example, if you have 16 chips on a 512mb stick of RAM doesn't that mean you have a chip density of 512mb/16 = 32mb per chip? And if you have only 8 chips on the 512mb stick, doesn't that mean you have a chip density of 64mb per chip? If my Biostar motherboard does not recognize half of my RAM with a chip density of 32mb then how is it possible for it to recognize the Crucial SDRAM with a chip density of 32mb/chip or 64mb/chip?

And BTW if my 512mb stick of RAM with 16 chips has a chip density of 32mb/chip, do you have any idea why is each chip marked 64x4SL8BTW?

[krazefinn]

Welcome to the opt, have you tried to run with only the one new stick?

In theory your explanation and understanding seems legit, but I would assume that board should also handle high density ram if it accepts 512 sticks. You may have something else going on, am assuming both slots are OK. Try the new ram alone in both slots...and also disable spd and try to manually set timings, to tune it for slight performance advantage when you do find the other half!

[Midknyte]

(#chips x chip depth M x chip width)/8 bits per byte = total memory

(16chips x 64M x 4)/8 = 512MB

Try a bios update with the old ram, then install the new stuff again.

[JRob]

Originally posted by Ol'Tunzafun
512MB dimms are all, necessarily, constructed from high density chips. If there are 16 chips on a 512MB dimm then the chips must be 32MB each, or as the chip manufacturers say, 256Mbit. (1MByte = 8Mbits).
The chipset on your board, as you can determine from the chart on the following site, cannot accomodate anything above a density of 128Mbit (16MB) chips.
http://users.erols.com/chare/chipsets.htm
In other words your board cannot fully utilize 512MB dimms and can only accommodate 256MB dimms with 16 chips.

Thanks for the reference to the chart. But it looks to me that my chipset Via VT8601T, listed under Via PLE133, which is the designation in my manual, shows a DRAM density of 16Mbit, 64Mbit, 128Mbit, and 256Mbit. So it should actually be able to handle the high density 256Mbit / 32mb chips. Which is consistant with the Biostar documentation and the Crucial recommended SDRAM.

[JRob]

Originally posted by Midknyte
(#chips x chip depth M x chip width)/8 bits per byte = total memory

(16chips x 64M x 4)/8 = 512MB

Try a bios update with the old ram, then install the new stuff again.

Thanks for the info. I think I'm beginning to get it now.

My existing BIOS VLQ1231B is the same as the latest BIOS update available from Biostar. Do you think a reinstall of the same BIOS might help? I have never updated BIOS before. It sounds not too difficult but I have heard that you can do damage if you don't know what you are doing. Is this the same as "Flashing" the BIOS? Will it affect everything installed on my hard drive?

[Ol'Tunzafun]

For example, if you have 16 chips on a 512mb stick of RAM doesn't that mean you have a chip density of 512mb/16 = 32mb per chip?

That's exactly right. It's not going to matter where you buy the RAM. Your board has the ability, it just needs an education.
Some of the late socket 370 boards could run 256 Mbit memory natively but some require BIOS updates to do so.
http://www.biostar-usa.com/mbdownloads.asp?model=M6VLQ
Update your chipset drivers while you are at it.

And if you have only 8 chips on the 512mb stick, doesn't that mean you have a chip density of 64mb per chip?

Well, so it would appear, but what you are seeing is actually 2 - 32MB chips laminated together. If you look closely at them, you will see that they are much thicker. So it is still 256Mbit density.

[Midknyte]

reflashing won't help, so I wouldn't bother. it's not like your bios is corrupted or anything.

[JRob]

Originally posted by krazefinn
Welcome to the opt, have you tried to run with only the one new stick?

In theory your explanation and understanding seems legit, but I would assume that board should also handle high density ram if it accepts 512 sticks. You may have something else going on, am assuming both slots are OK. Try the new ram alone in both slots...and also disable spd and try to manually set timings, to tune it for slight performance advantage when you do find the other half!

Thanks, its good to have found you!

Yes I have tried the 512mb stick of RAM alone in both slots with the same result -- half of my RAM is not recognized. And I had to disabled the "by speed" default setting for the DRAM clock and had to set it to a manual setting of "host clock" in order for the machine to boot up properly. I had to reset the CMOS jumper after trying unsuccessful settings.

[Ol'Tunzafun]

Does this mean that you are seeing all of the 512MB now?