Archived from groups: alt.comp.periphs.mainboard.asus (
More info?)
In article <n235o05qu89gjt25j630d962n354qur920@4ax.com>,
husker3in4@*no*spam*yahoo.com wrote:
> Im about to get a new board. I've used the i865 in the past, and
> had no problems with it. The 875 is more expensive, so I'm
> assuming its better. Some of the benchmarks that came out when
> both chipsets were new show not much if any performance
> differance. What warrants the higher price on the i875 chipsets
> then? I do alot of gaming on my computer too. Can anyone
> offer any insight? Thanks.
875 and 865 are made from the same silicon die. They are
sorted by speed, and the faster ones (the ones that can guarantee
the PAT timing) become 875. The others become 865 or some
other chip. 865 is still tested for operation at FSB800, but
don't expect the same overclocking properties.
The PAT timing is guarantee at DDR400. Motherboard manufacturers
found a way to get the 865 into the same mode of operation as the
875, but you don't have an iron clad guarantee that the internal
timing is the same on the 865.
In terms of user experience, 865 users have "video artifacts",
when running a CPU clock of 250MHz (overclock) versus the
nominal 200MHz clock used for FSB800 operation. Search Abxzone.com
forums, for a poll conducted by the users, as to how many of
them experienced this problem. There is nothing wrong with the
865 at nominal settings. Some have found that the RAM makes
a difference, and this could in fact be related to the paragraph
above.
The 875 has more pins on the bottom of the chip than the 865.
The die inside the 865 has the signals, but they are not pinned
out and cannot be used. The pins include:
1) Parity signals for the memory busses. The 875 can use unbuffered
DDR with parity chips (x72 DIMM).
2) Both chips have a 266MB/sec MI-1.5 bus, that connects to the
Southbridge. The 875 has an additional 266MB/sec MI-1.5 bus, and
that is used on motherboards, as a private bus for a gigabit
Ethernet chip. While this may sound nothing short of amazing,
the actual utility of this is debatable. If you use the 875 to
build a file server, it might be worth it. For gaming, it makes
no difference. This extra bus is known as "CSA" in the literature.
In summary, buy the 875 if you want no-holds-barred overclocking
capability. Buy the 865 if you want a stable board that will never
be overclocked to any significant extent. If you want to save a
few bux, overclock the 865 like crazy etc., do lots of reading on
Abxzone, to find out how best to achieve that goal. For example,
the 865 chips on early date code motherboards, were every bit as
good as the 875 chips. It is suspected that Intel wasn't "binning"
chips in the beginning, so in terms of speed, they were closer to
being the same. The evidence is, later boards (like anything you
buy new), will use the sorted chips.
HTH,
Paul
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