RAM for Biostar M7VIG Pro

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My apologies for asking essentially the same questions about RAM, that I
had previously.  This time, though, it's a different mainboard and I
want to make sure I don't purchase the wrong doodads.

Here's the mainboard in question:


I'm looking to pick up about 256Mb of RAM, which (I think) should be
enough to comfortably run a light-use install of Windows 2000.  There is
currently 96Mb on board, but I do not, as yet, know in what
configuration. (I'll be getting those details soon of it's of any
importance to anyone.)

Basically I'm thinking that I can get two 128Mb sticks, for whichever
pair of slots is the least populated, and recycle at least 64Mb of the
existing RAM.

Q1) Is there a performance advantage to PC133 or DDR266?  I see at the
128Mb level, that PC133 is generally a bit more expensive.

DDR 266 at NewEgg:
http://www.newegg.com/Product/ProductList.asp?Submit=ENE&N=2010170147+1052107965+105231444+1052407861&Subcategory=147&description=&srchInDesc=&minPrice=&maxPrice =

PC 133 at NewEgg:
http://www.newegg.com/Product/ProductList.asp?Submit=ENE&N=2010170147+1052107967+105231444+1052407863&Subcategory=147&description=&srchInDesc=&minPrice=&maxPrice =

Q2) What Cas Latency should I be looking for?

Thanks for your time and consideration.

Re: RAM for Biostar M7VIG Pro

Grinder wrote:
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The speed hardly matters because the CPU's L2 cache handles almost all
the memory accesses, but I would prefer DDR RAM simply because the
price is about the same, and you'll be able to use it in other current
mobos.  But I buy memory only from local dealers that give 100% cash
refunds because I've experienced high rates of  failures with modules,
including brands like Kingston, Mushkin, and K-byte.  Local prices can
be found at www.saleshound.com and www.salescircular.com, but they
often miss Fry's specials.

I don't know what the largest modules your mobo supports, but it may be
better to run Windows 2000 or XP (BTW, OfficeDepot has XP Home for $40,
after rebate, through 7/1/2006, $20 if you use a $40 off $100 coupon
and buy some paperclips as well -- see "Hot Deals" forum at
www.fatwallet.com).  with 512MB, and this is often the cheapest size
module on a per-byte basis.  I've been using PC3200 memory, even in
DDR266 (PC2100) mobos, and have never had speed-related problems with
it, except when I configured the BIOS for its safe default settings,
which cause a VIA-based mobo to lock up and its integrated video to
display white vertical bars that slowly increased in width.  There were
no problems at the normal default settings.

Because memory quality is so bad now, I strongly urge you to test all
memory overnight using the diagnostics from both www.goldmemory.cz and
either www.memtest86.com or www.memtest.org (same thing, only updated)
because these are the best freeware/shareware diagnostics available
(see www.realworldtech.com review), and I've had two modules fail one
diagnostic but not the other.  Test at both the memory module's default
settings and the BIOS' defaults, but realize that they aren't
necessarily the same, even when the BIOS is set to use automatic/SPD
memory timings.  You may have to read the memory's tiny SPD chip with a
utility like CPU-Z or Thaiphoon and manually configure the BIOS for
testing.   Also just because PC3200 or PC2700 memory works reliable at
PC2100 speed doesn't necessarily mean it will be good at PC2700 or
PC3200 speeds, as I learned from 2 out of 2 Mushkin PC3200 modules.
Reject any memory that shows any errors at all,  unless the errors were
caused by improper configuration (including overclocking) or bad
hardware (poor connections, bad power supply, etc.).

Re: RAM for Biostar M7VIG Pro

On Tue, 27 Jun 2006 22:48:33 GMT, Grinder

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Yes it will be, though as always a little more is a little
better.  Win2k uses about 64mb less than XP, give or take so
anyone needing 512MB on XP would need about 448 on 2K.

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The board can run PC133 or DDR266/333/400 but not both types
simultaneously.  It is not a dual channel board so your best
choice is CAS2.5 PC3200, one 256MB module (given your desire
to have 256MB, but frankly I'd go ahead and get 512MB
instead, memory is rather cheap these days).

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Yes, DDR266 is faster, particularly if you are using the
integrated video it can be up to 1/3 faster (older games) or
higher-res video playback.  For less demanding typical PC
uses it'll probably be closer to 6% difference, more or less
depending on how much the rest of the system is a

Though I wrote DDR266 (because you did), we're actually
talking about PC2100.  Since memory is backwards compatible
and since CAS2.5 is now reasonably priced, your best bang
for the buck is buying CAS2.5 PC3200 and running it as CAS2.
This is because the typical CAS2.5 PC3200 is actually spec'd
to do CAS2 @ PC2100 speeds in it's SPD table.  As with any
memory upgrade you should run memtest86+ for several hours
to confirm stability.  You can see the contents of the SPD
by using Everest?, Sisoft Sandra or perhaps CPU-Z... I'm
sure one of these 3 does show more than just the spec for
the labeled spec of PC3200.

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Get the cheapest PC3200 CAS2.5 at newegg, about $20, or
this: (might be CAS3, but even so doubling memory for $10
more AR would be worthwhile.)

Re: RAM for Biostar M7VIG Pro


kony wrote:
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Here's what NewEgg has:
$38.49 + $4.99 shipping

 > (might be CAS3, but even so doubling memory for $10
 > more AR would be worthwhile.)

I'm sorry, I'm not getting what you're saying here.  What might be CAS3,
and what is AR?

Re: RAM for Biostar M7VIG Pro

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AR = after rebate

CAS stands for column address strobe, and CAS Latency, is the
delay from when you ask for your data from the ram, until it
shows up.

A PC3200 memory runs at DDR400, which is two data transfers
per each cycle of a 200MHz memory clock. A 200MHz clock signal
has a period of 5 nanoseconds (billions of a second). When
the memory is rated PC3200 CAS3, that is 3 cycles * 5ns = 15ns
delay until you get your data (the first cycle of the burst
of returned data).

Now, say we reduce the clock signal to the memory. We drop the
clock to 133Mhz (or stated another way DDR266 transfer rate).
The period of a 133MHz clock signal, is 7.5ns. To figure out
the new CAS number, take the total CAS time (15ns) and divide
it by the clock period, selecting the next largest half-integer
number of clock cycles, if the result doesn't divide exactly.
In this case 15ns/7.5ns = CAS2 when that memory is run at DDR266.

In other words, a PC3200 CAS3, when operated at the lower speed,
becomes PC2100 CAS2, and CAS2 is as fast as you can go. So, if
buying a faster RAM, with the opportunity to run it slower, the
memory is good enough if it is CAS3.

Now, we'll try a different stick. Take a PC3200 CAS2.5. For that
one 5ns * 2.5 = 12.5ns. Now, slow the stick down to PC2100. The
clock in that case is 7.5ns. 12.5/7.5 = 1.67, and rounding up
to the next half integer would be CAS2.0. The stick runs at
CAS2, but it has a little extra margin, and actually has the
data ready before the second clock cycle is completed.

If we really went crazy, we could buy PC3200 CAS2. For that
one 5ns * 2.0 = 10ns. Slow the stick down to PC2100.
10ns/7.5ns = 1.33 cycles, rounded to the next half-integer
higher makes it CAS1.5. There is no such thing, and attempts
to run at CAS1.5 on Tomshardware in the past, showed no diff
between CAS1.5 and CAS2. So, again, the PC3200 CAS2 ends up
running at PC2100 CAS2, but with plenty of time remaining in
the second cycle before the data is needed. Even more time
margin is present.

So buy some PC3200 CAS3 or CAS2.5 and you should be fine.
The most stable memory configurations are with the fewest
number of sticks, so one stick of 512MB, as long as it
fits within the maximum size limits of the chipset (1GB
in this case), then the memory should work. If some day
you want to buy a 1GB sized stick, buy a stick that uses
64Mx8 chips, because the super-cheap sticks that use 128Mx4
chips, may not work properly.

If you want a primer on DDR memory, there is a slide show here.
The slide set is a mixture of propaganda and some facts.



Re: RAM for Biostar M7VIG Pro

On Wed, 28 Jun 2006 06:11:06 GMT, Grinder

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That should be fine.  There's always an outside chance the
board has some bios or general layout bugs but so could
anyboard, you can only buy the part and test it as usual.

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The memory didn't have the cas rating listed, or I was not
looking hard enough to find it.  Often brands like Kingston
will get rid of their CAS3 stuff in local stores at same
prices as anybody else's CAS2.5, but the prior link had a
rebate involved and free shipping (IIRC) so it ended up
cheaper (A)fter (R)ebate.

Re: RAM for Biostar M7VIG Pro

kony wrote:
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Thanks guys, you've been very illuminating.

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