SDRAM memory - Which of these is best? Compatiblity?

[Slickone]

This all the extra memory I have. Trying to decide what to do with each. Please put these in the order from best to worst. Any notes as to why welcome. (Semicolon separates lines)

PNY 32MB PC100 4x64

Crucial 256MB PC133 32Mx64

K-Byte 256MB PC133 32Mx64

Centon 256MB PC133(Only) 32x64-7ns
"Not backwards compatible to PC100."

Kingston 128MB PC133
Chips = 16Mx6 SDRAM-7.5-1 (that's it)
On memory card package = KVR-PC133/128-R
On sticker stuck to 2 chips = ValueRAM; KVR-PC133/128-R; 740617047042
On sticker stuck to chip = 9902364-015.A01; 1038494-3.3V; ASSY IN USA
On box = 047042US under bar code.
Box says "All systems using 440BX, 810, or 810e chipset should only use PC100 memory. PC133 are not backward compatible to PC100 machines".

Kingston 256MB PC133
Chips = Infineon; HYB39S128800CT-7.5; C2 SVV27301; written vertically = 0124
On package = KVR133X64C3/256; CL3
On sticker stuck to 2 chips = ValueRAM; KVR133X64C3/256
On sticker stuck to chip = 9902112-438.B01; 675923; ASSY IN TAIWAN

Kingston 128MB PC133
Chips = hynix 241A A; HY57V561620BT-H; KOREA AS36462PK
On sticker stuck to 2 chips = ValueRAM; KVR-PC133/128
On sticker stuck to chip = 9902364-015.A01; 1050431; ASSY IN CHINA

Kingmax 256MB PC150
Chips = KINGMAX; KSV684T4A1A; -06; written vertically = 110398A
Sticker on chips = MPJB63S-683; P120132.02KX; PC-150
On PCB = Made in Taiwan

Also what is the chip density of the last three?
Are the ones made in China not as good?
I thought PC133 was supposed to be backward compatible with PC100. Why are some not?
Anyone know which will work in a friend's Compaq Presario 2256?

 

[LordMagnusKain]

i thought PC133 was supposed to be backward compatible with PC100. Why are some not?

they are.

if they are specked t run at a mhz they will, at that and lower;

manuf makes no diference, as per anandtech artical i read back before DDR memeory.

 

[Slickone]

Then why do two different ones I listed state they wont work in PC100 systems?

Anyone care to tackle the other quesions?

 

[mechBgon]

I would regard the Crucial as the best of the four. All the Crucial PC133 I've bought has worked at 100MHz in motherboards that only take lower-density memory (boards as far back as the i440LX chipset). They may now be using higher-density chips for reduced cost of production, however. Read this FAQ for the reason that some PC133 won't run in some boards.

Crucial's memory configurator only guarantees one module for use with your friend's Presario 2256: click here It appears to only have one SDRAM slot available and maxes at 64Mb of RAM, according to page 3-11 of this document showing the motherboard, so try your 32Mb PNY module in it.

 

[Lord Evermore]

Because if everybody only bought PC133, they couldn't get rid of their PC100 stocks.

Memory might not run at a lower speed is if the board is proprietary and the BIOS will only read the memory SPD (not let you set any memory settings), and will only work if the SPD reads the exact speed the board wants to see. That's unlikely on most OEM systems and consumer boards these days, and for a few years.

Some memory module SPDs may actually not be programmed as completely as you'd expect, which I think is why some types say not to use them on slower boards. For example a PC133 module may only have settings for 133MHz programmed into it. When installed in a board that only goes up to PC100, if the chipset reads the SPD and only finds PC133 settings, it won't know what to do, because it doesn't even know what PC133 is -- it can't even understand that a 133MHz module can run at any other speed, it depends on the module to tell it what to run at.

However, even with that "semi-programmed" SPD, if the BIOS allows you to set the memory speed manually, you should be able to use PC133 memory.

The Presario 2256 is only a PC66 system, so if the BIOS doesn't allow you to control the speed manually, it may not accept even PC100 modules. Also, the Presario only accepts up to a 32MB module apparently, up to a maximum of 64MB (with 32MB built into the board, so you can only add 32MB total).

No idea what the density of the last two are.

I don't think there will be much difference between chips made in China. Hynix is a well known manufacturer who just happens to have foundries in China.

 

[bozo1]

Then why do two different ones I listed state they wont work in PC100 systems?

Because they use 'high-density' chips which will not work on Intel chipsets. If your system uses PC100, there is a good chance it contains an Intel chipset.

 

[Lord Evermore]

bozo1 has it. I always forget about density issues, especially with smaller module sizes. The speed isn't the issue, just the type of chips they used.

 

[Slickone]

Regarding the FAQ mechBgon linked, which says 32M x 4 is high density. Is says anything ? x 4 is high density. So are the 32M x 64 I listed not high density, or the 16M x 6? Or is it the 32M and up that tells it's high density?
Even if if any of these (besides the PNY) is not high density, they still work work in my old Abit BH6 BX chipset (overclocked to 100 FSB), since the FAQ says the early BX had a limit of 64Mbit and even the 16Mx6 Kingston I listed is 96Mbit ? My BH6 is revision 1 I think. Would this have the early BX chipset the FAQ is talking about? Wish I knew the density of the other Kingstons. The FAQ also says high density won't work in early BX chipsets.
And I assume what won't work in my BH6 won't work in his Compaq (even w/out the 32MB limit) I assume. Anyone want to do some trading for their older chips?

So the cheaper ones lack the electronics to tell the BIOS that they can run at lower speeds?
Really though, them saying they can't work in any PC100 systems is something different than saying they can't work with certain chipsets because of memory density, is it not? Why don't they just say that? That if there is a chance a PC100 chipset could not be intel.

BTW, these are sealed so I'm trying to figure out what will work without opening them up and trying, for higher resell.

 

[Lord Evermore]

You can figure out the density of the chips base on how many chips there are on it and the size. If it's got 8 chips on both sides and is 256MB, that means they're 128Mbit chips (8 bits makes a byte, so 8 chips with 128Mbits makes 128MB). If it's a single set of 8 chips and 256MB, that means they're high density 256Mbit chips. A 128MB module with 8 chips means 128Mbit chips, not high density. Figuring out the density based on the "32Mx64" or other markings may be a bit harder.

The FAQ needs to be updated (it's a year and a half old) since current Intel chipsets certainly do support high density memory.

However VERY old chipsets may not even support that. The chipset in the Compaq is probably something like an Intel Triton series or possibly one of VIA's SuperSocket7 chipsets. When those came out, 128Mbit was considered a huge memory chip goal. The 32MB PNY module may work fine, as it's probably something like 4Mbit x 8cells.

As the FAQ mentions though, the 810 chipset supports 256Mbit high density modules, so even if the Kingston module is, it would still work in an 810 board.

Apparently there are two ways that manufacturers refer to the organization of the chips. In order to figure out which way is which, you need the organization as well as the number of chips used.

This PDF gives a table listing the difference densities of chips, module sizes and organizations (on page 23). They refer to registered DDR modules, but the same applies to unregistered and SDR memory, and it lists for ECC and non-ECC. However this is only the organizations for the higher density modules, x8 and x4. As the FAQ mentions, it is possible for lower densities to exist, but newer modules won't be using those. There really is no way to tell by the markings unless the chip or module specifically states the organization, or you can look up the part numbers and get the information.

If a module has "32Mx64" (which refers to the module organization, not the chip organization) listed on it and is 256MB total size, and has 8 chips then the chip organization is 32Mx8. (It could also technically be 64Mx4, or possibly 16Mx16 but I think they moved to x8 before reaching the 16Mbit per cell level.) That would be high density, since each chip's cells are 32Mbit. If it has 16 chips and the same module organization, then the chip density is 16Mx8, not high-density as far as chipsets since the later BX revision and VIA's KT133 chipsets are concerned, because each chip is only 128Mbit. (But it could be 32Mx4, which would be high density.) There really is no way to be sure of the density without being specifically told on the markings or by looking up the chip information.

A 128MB 16Mx64 module with 8 chips uses 128Mbit chips, which may be high density to very old chipsets. A module with 16 chips uses 64Mbit chips, which should be supported by older chipsets.

A 32MB 4x64 module with 8 chips means each chip is only 32Mbit in size, with an organization of 4Mx8 for each chip, very low density indeed.

I think the Kingston "16Mx6" chips may be a misprint or something, and they're actually 16Mx64.

What all this means is you can pretty much ignore anything saying x64 or x72 (for ECC), because it tells you nothing. All 256MB non-ECC modules are 32Mx64, and it's the number of chips that will tell you how dense each chip is. All 128MB modules are 16Mx64. Unfortunately, most of the time you can't tell ahead of time how many chips there are.

If you see anything referring to lower numbers like x8 or x4, then you can figure out what the density is as well as how many chips it uses.

It's not necessarily the "cheaper" modules that don't have the SPD programmed for other speeds. It's just a cost issue for the makers, because it costs more to put a SPD on that is programmed for speeds all the way back to 66MHz when most people don't need that anymore. Whether they should label the reasons that it won't work with older chipsets is a matter of opinion. As far as the manufacturer is concerned, most people are going to want to install the module and not do anything else and expect it to work; they won't understand if the package explains that you need to check what your BIOS is capable of and verify the type of chipset you have, and tells you what the density is so you can figure out if it will work. So it's easier for them to simply specify that it won't work, and get you to buy "rare" PC66 memory modules that may expensive one day, or that they would like to get rid of stocks.

 

[Kingofcomputer]

??x4 is not really high density.
32x?? is high density comparing to 16x??.

??x8 is the common type, every chipset can use it.
??x4 and ??x16 are the less common type, not every chipset can use it.

 

[Slickone]

Whew, thanks for the time spend on your reply, Lord Evermore.
So are you saying you have no way of telling from the chip #'s I gave whether any of these 128 or 256 DIMMS will work in my 1st revision Abit BH6 BX chipset or not? The Kingston's I can't tell if they have any chips on the back or not without opening them up. The Kingston 128 have 4 showing on one side, the Kingston 256 has 8 showing on one side. The K-Byte and Centon 256 each have 8 total. The Crucial 256 has 16 total.