Re: DDR Confusion
- From: Paul <nospam@xxxxxxxxxx>
- Date: Sun, 09 Nov 2008 02:19:50 -0500
The more I Google, the more confused I get.
I'm trying to upgrade the RAM on a five-year-old Biostar M7VIG Pro-D motherboard with an Athlon XP 1900+ processor. Specs say it maxes at two modules of 1GB DDR266 PC2100, and that's what I'm looking for. Currently, I'm using two 128MB PC2100 modules. They're working just fine, but with my last Linux update I'm seeing signs that it's getting cramped in there.
I bought a PNY 2GB PC3200 kit from Newegg ($42.99, free shipping), but I had problems with it. It was supposed to be compatible with PC2100, even stated so on the package. It installed fine, and the BIOS recognized the full 2GB from the start - as did Mandriva 2009.0. But, after a few minutes things started crashing, until the whole system crashed. Rebooted - same result. Re-installed the old RAM, and Mandriva was again as rock-stable as ever. I don't know if the modules were incompatible, or just defective, but I RMA'ed them as "incompatible," and shipped them back to Newegg today.
I'm beginning to wonder if it's the high/low density thing that's the problem. PNY's FAQ states that they only use high density chips these days, and my board is supposed to use low density chips, I guess. But, my reading indicates that the most usual density symptom is non-recognition of all the memory - and my board saw it all.
Crucial lists a PC2700 module as compatible, and Newegg will sell a pair of them for about the same as the PNY kit. However, a couple of the over 100 reviewers said they had problems similar to mine, and the Crucial specs say "128M x 64," and at least one forum I visited (God knows where - seems like I've been to hundreds) said that 128M anything is high density and won't work on many older boards like mine. But over 100 customers had no problems, and they include other brands of boards as old as mine. I might try it on the strength of Crucial's memory finder, but Newegg already has ONE restocking fee out of me - I don't want to shell out more.
My head's beginning to hurt, and aspirin isn't helping. Can anybody clear some of this up?
Run memtest86+ from memtest.org on one stick at a time. Place a single
1GB stick, in the slot furthest from the processor. Then run memtest86+
for at least a couple passes. That will help you identify if just one
stick is bad. Then you can install both again and retest.
In a 1GB DDR module, (16) 64Mx8 is low density. (16) 128Mx4 chips is
high density. The (16) 64Mx8 configuration, consists of two ranks
of memory, one per side of the module. The other form, the (16) 128Mx4
chips, is a single rank which takes up both sides of the module.
(The x4 part, refers to the memory chip width, and that would be
a four bit wide chip. The x8 chips are eight bits wide. You
use enough chips, to build a 64 bit wide rank, and if there is
room left on the module, you can build a second rank.)
Intel chipset documentation, generally approves of the 64Mx8 kind,
but not the 128Mx4 kind. Thus, branded memory makers (PNY, Kingston,
Crucial etc), will try to make memory which works with all chipsets.
They don't have an incentive to make memory which is "half-compatible".
The 128Mx4 chip type of DIMM is typically found on Ebay. For branded
types of RAM, such as your PNY brand, they generally don't want to get
caught making the kind with the 128Mx4. In the Ebay adverts, they
sometimes call the product "Samsung", but they're referring to the
brand of the chip itself. The module maker is unnamed, to protect
Some motherboards have an adjustment for Vdimm. DDR normally takes
2.5V, but some motherboards allow adding voltage in 0.1V increments.
My previous motherboard used to run at 2.65V for example, and I
generally didn't have a problem with memory errors. (I tried downloading
both manuals for your motherboard, but there are no details about the
BIOS in the manual.)
When buying memory, I like to read the reviews on Newegg before
buying. That allows me to detect poorly tested product. Or,
product that fails in a short period of time. You'd be surprised
how some branded products fall into those categories, and the
last time I was shopping for RAM, it took me two hours of
reading reviews, until I found a good compromise product.
What that means is, perhaps other people have had trouble with
that particular part number of memory module. So looking it
up on Newegg, may give you some idea what to expect.
The last DDR I bought was some OCZ. The last DDR2 was
Kingston. Previously, I've bought a lot of Crucial RAM.
But check the reviews, because anybody can have a bad day.
(I never thought I'd see Crucial have trouble shipping
good product, but it even happens to them.)
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