DDR Memory Q

[jmucchiello]

If your motherboard requires DDR 1600 DIMMS can you use higher rated DIMMs (2100, 2400, etc) in it?

 

[Doh!]

Yes.

 

[Corporate Thug]

yes, it will just run at 1600. btw, what is that? pc200?

 

[Peter]

A clear Yes. There is no lower limit to SDRAM operating speed - be that SDR or DDR.

PC1600 is running at 100 MHz DDR, aka "DDR200" for those who believe in "marketing MHz".

 

[jmucchiello]

Then why do they still sell 1600 RAM when it usually costs more than the more current RAM? Is it just to gouge people who can't ask questions at a site like this?

 

[AndyHui]

Originally posted by: jmucchiello
Then why do they still sell 1600 RAM when it usually costs more than the more current RAM? Is it just to gouge people who can't ask questions at a site like this?

Probably.

 

[Peter]

Absolutely. Just look at how many shops charge a premium for "rare" PC100 SDRAM.

 

[jmucchiello]

Great. Thanks a lot.

 

[jmucchiello]

Originally posted by: Peter
Absolutely. Just look at how many shops charge a premium for "rare" PC100 SDRAM.

Actually I just got burned by this. I bought some PC133 SDRAM for a machine spec'd for PC100 SDRAM and the system doesn't recognize the DIMMs. It had a single 128M PC100 DIMM and replaced it with two 256M PC133 DIMMs and got a memory on boot. Tried the new DIMMs one at a time. Nada. Mixed the pc100 and pc133 DIMMs and the BIOS only reported 128M of ram and that the other DIMM slot was empty.

Any way to fix this?

 

[Boonesmi]

Originally posted by: jmucchiello

Originally posted by: Peter
Absolutely. Just look at how many shops charge a premium for "rare" PC100 SDRAM.

Actually I just got burned by this. I bought some PC133 SDRAM for a machine spec'd for PC100 SDRAM and the system doesn't recognize the DIMMs. It had a single 128M PC100 DIMM and replaced it with two 256M PC133 DIMMs and got a memory on boot. Tried the new DIMMs one at a time. Nada. Mixed the pc100 and pc133 DIMMs and the BIOS only reported 128M of ram and that the other DIMM slot was empty.

Any way to fix this?

the problem isn't the fact that the new memory is pc133

most likely your board only supports low density dimms and the stick of pc133 that you bought is probably high density (you can buy low density pc133)

 

[jmucchiello]

Originally posted by: Boonesmithe problem isn't the fact that the new memory is pc133

most likely your board only supports low density dimms and the stick of pc133 that you bought is probably high density (you can buy low density pc133)

Motherboard specs say it supports up to 512M and there are only 2 DIMM slots on the board so why wouldn't 2 256M DIMMs work/be recognized?

 

[Peter]

Once again: The speed grade doesn't matter. However, there are plenty more possible incompatibilities between a board and a DIMM. SDRAM chip density too big, unsupported SDRAM chip geometry, wrong type of DIMM (unbuffered vs. registered, ECC vs. plain), that stuff.

What board do you have there, what DIMMs have been in there, and what DIMMs did you try to put in?

 

[Boonesmi]

Originally posted by: jmucchiello

Originally posted by: Boonesmithe problem isn't the fact that the new memory is pc133

most likely your board only supports low density dimms and the stick of pc133 that you bought is probably high density (you can buy low density pc133)

Motherboard specs say it supports up to 512M and there are only 2 DIMM slots on the board so why wouldn't 2 256M DIMMs work/be recognized?

im not talking about dimm size.. i was saying your board probably doesnt support high density dimms (you can buy low density 256mb pc133 dimms)

 

[jmucchiello]

Originally posted by: Boonesmi
im not talking about dimm size.. i was saying your board probably doesnt support high density dimms (you can buy low density 256mb pc133 dimms)

What measurement indicates density? This is the information I have from hp: hp.com

 

[Boonesmi]

Originally posted by: jmucchiello

Originally posted by: Boonesmi
im not talking about dimm size.. i was saying your board probably doesnt support high density dimms (you can buy low density 256mb pc133 dimms)

What measurement indicates density? This is the information I have from hp: hp.com

its not a measurement
you need ram that specifically states "low density"

 

[jmucchiello]

So it is assumed to be high denisity? Is there any way to be sure? Could the same problem occur with PC100 SDRAM?

 

[kamper]

So it is assumed to be high denisity? Is there any way to be sure? Could the same problem occur with PC100 SDRAM?

Bump! I'd like to know the anser to this question too.

 

[Peter]

Unless you tell us what we asked you for, we'll never know. What's the chipset on your mainboard, what DIMMs have been in there before, and what DIMMs were you trying to put in? (Note: Total DIMM size is NOT a sufficient answer. We need brand and model here, down to what the individual SDRAM chips are.)

And once more, yes, the issue is independent from the speed grade.

 

[kamper]

So it's pretty much a crap shoot any way you look at it?
That's all I needed to know.

 

[Boonesmi]

Originally posted by: kamper

So it is assumed to be high denisity? Is there any way to be sure? Could the same problem occur with PC100 SDRAM?

Bump! I'd like to know the anser to this question too.

if i remember right pretty much all pc100 is low density (but im not 100% sure about that)

most of the newer pc133 is high density

 

[Peter]

Hell no. Sure, most of today's stock is made from 256-Mbit density SDRAM parts that happen to also be PC133 speed grade.

Likewise, today's premium price rarity offers of PC100 SDRAM are created by peeling "PC133" stickers off and slapping "PC100" on instead. A perfectly fine step, since every PC133 DIMM inherently also fulfills PC100.

There you have it. "PC100" does _not_ imply a certain maximum density of the SDRAM chips used, neither does "PC133". You need to watch BOTH these properties, density/geometry and speed grade, to get a compatible DIMM. If your vendor is incapable of specifying what you get, buy elsewhere.

 

[jmucchiello]

All that I know about the motherboard is what is available on the HP.com website. The system is a HP Pavillion 511w. The link I posted above is as technical as the details I have get.

Memory: PNY 256M SDRAM

Sticker:
256MB, SDR DIMM,H
32WHS PO 117299.15

Chips:
DF 0334
S80032LLCTW
-75A

Memory: Centon 256M SDRAM

Sticker:
CENTON Electionics, Inc
256MB 154909
256PC133ONLY
HITCT8VUA

Chips:
hynix 236A
HY56V56820BT-H
Korea 7B23058KV

So, I'm guessing the H on them tells you the density. Next time I open that machine I'll have to look at what the DIMM it came with says.

 

[Peter]

Those "DF" chips I can only guess that they're 32x8 geometry, hence 256-Mbit devices.

The Hynix chips are 256-Mbit as well (from the V56 bit in the product code).

The "-H" just means PC133 CL3 speed grade.

Now, you got an Intel 810 chipset there. Its limit is 128 Mbit technology, so there you have your reason why these DIMMs won't run: Each SDRAM chip is twice as big as the chipset can handle.

If you want to get 256-MByte DIMMs for this machine, they need to be double sided, 8 chips on each side, each chip being "16x8" geometry 128-Mbit.

As I said, buy from a vendor to whom the stuff in the previous sentence means something.

 

[jmucchiello]

See, that answers my question. I need to look at the chip geometry. That's the part I had forgotten (it's been years since I've upgraded a machine. Them Celerons ain't like those 486 boards I'm use to. ) And it explains the greater (theoretical) expense: there are more chips on the circuit board.

 

[Peter]

The price delta mostly comes from the fact that the majority of DRAM currently made is 256-Mbit. 128-Mbit is already on its way out, despite most older and some silly recent chipsets requiring them. Economy of scale, with supply and demand piled on top.