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Boy, what a ride the last few months have been. While the star
of ATi had fallen considerably with the launch of the R600-based HD
2900 XT, they have more than made up for it with the launch of the
RV770-based 4850 and 4870. While nVidia was basking in the
glory of the GTX-260 and GTX-280, ATi came out of nowhere and completely took the wind
out of their sails with the price-performance friendly 4000 series.
In turn, nVidia responded by slashing prices and launching the
9800GTX+.
Of course, ATi has a counter-punch ready, and it is being unleashed
on nVidia's chin today. It is the R700 based 4870X2, and we
are going to see if lands squarely, or if it is a whiff.
Before we start in on the benchmarks, let us look at what is behind
the R700 and what it can bring to the table.
|
4870X2 |
4870 |
4850 |
|
Stream Processors |
800 x
2 |
800 |
800 |
|
Texture Units |
40 x
2 |
40 |
40 |
|
ROPs |
16 x
2 |
16 |
16 |
|
Core Clock |
750MHz |
750MHz |
625MHz |
|
Memory Clock |
900MHz GDDR5 |
900MHz GDDR5 |
993MHz GDDR3 |
|
Memory Bus Width |
256-bit x 2 |
256-bit |
256-bit |
|
Frame Buffer |
1GB x
2 |
512MB |
512MB |
|
Transistor Count |
956M
x 2 |
956M |
956M |
|
Manufacturing Process |
TSMC
55nm |
TSMC
55nm |
TSMC
55nm |
|
Price Point |
$549 |
$299 |
$199 |
As we can see from the above table, the 4870X2 is exactly what it
says it is; two 4870s crammed onto a single card, with one
exception. While the standard 4870 is equipped with 512MB of
RAM, the 4870 has 2GB of GDDR5, all running at 900MHz, or 1800MHz
effective. This is fairly impressive, as most dual-GPU cards
end up toning down the clock speed in order to keep heat in check.
A couple other items here are also worth taking note; there have
been lots of rumors about the R700 being the first card to utilize a
unified frame buffer, considered by many to be the holy grail of
multi-GPU gaming by making the memory core agnostic, and thus much
more efficient. It turns out that this is not the case for the
R700, we are still going to have to wait for that, however, AMD has
hinted that there is some GPU to GPU communication going on in the
R700 that promises to make it more efficient than the typical two
card Crossfire setup.
Before we continue on, I must admit that I have never been a fan of
multi-GPU setups. Too often, there has been issues with price
to performance ratios, driver problems, and compatibility, not to
mention heat and power consumption. In a sense, multi-GPU has
always seemed "half-assed". With that being said, we will be
taking a very close look at the 4870X2 with a critical eye, and we
will see if AMD can sway me over to the multi-GPU camp.

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