It makes sense to break
things down a little further for you at this
point. Let's have a closer look at the chip
level components on these two modules and what kind
of specifications they bear.
let's look at Mushkin...
are 7ns. 8MX8 Synch. SDRAM chips. Here is a
table of their timing characteristics courtesy of Mosel
see a Clock To Access Time of 5.5ns. and support for
CAS Latency of 2 performance up to 143MHz.
Remember, these are chip level numbers. When
there are several of these parts on a module, other
timing issues come into play like chip to chip
timing, so specifications at the module level may be
let's look at Corsair's module with Micron on
to the Mosel chips, these are also 7ns. 8MX8 SDRAM
rated at 7ns. Here are their timing tables
courtesy of Micron
module has the "-7E" parts on it, as you
can see in the picture above. Here we see
slightly less aggressive timings with a CAS2
Allowable Operating Frequency of 133MHz. Now,
with this in mind, "specsmanship" between
Semiconductor Manufacturers is a delicate
game. Micron may just be a little more
conservative in the way they characterize their
parts. Still, looking at the specs, it seems
as though the Mosel devices can handle a CAS Latency
setting of 2 up to 143MHz. and the Micron only up to
/ Comparison Between CAS2 and CAS3
what's the big deal?
Here is a quick look
at what sort of performance gain CAS2 versus CAS3
settings can produce.
latest and greatest
Mid Tower ATX Case w/ 300W PS, Pentium III
MS6337 i815 Motherboard and nVidia GeForce2
Ultra, 128MB of PC133 True CAS2 SDRAM from
Corsair and Mushkin (thanks Outside
Loop), IBM 15Gig 7200 RPM ATA100 Hard
Drive (thanks again Outside
Loop), Kenwood 72X
98SE, DirectX 7.0a
we'll get a 10,000 foot view of performance from
SiSoft's Sandra Memory benchmarks.
first thing to note is that when all things are
equal, bus speed and CAS Latency settings that is,
both modules perform identically. The next
thing to note in the CAS3 scores (taken only on the
Corsair sticks) is there is a fair amount of
bandwidth lost. Even at a 160MHz. FSB, the
CAS3 timings can't keep up with CAS2.
does this affect real world performance?
That's what we have in store next...