After months of waiting and speculation, AMD has finally taken the lid off its RX
Vega
series, its clock speeds, capabilities, and pricing. All of these
characteristics have been hotly debated of late, with readers asking for
(and making predictions about) how it would compare with Nvidia’s
year-old Pascal GPUs like the
1070 and
1080.
We now have some preliminary answers to some
of those questions, but by no means the entire picture. So here’s how
this is going to work: If you want a “regular” GPU, you’ll be able to
buy the Vega 56 (56 active CUs) for $399. If you want the full Vega 64
chip (the air-cooled variant) you’ll be able to buy that for $499. I
will admit to being reasonably right in one regard — I predicted that a
1.7GHz base clock for RX Vega made good sense if Vega FE was a 1.6GHz
chip. The actual boost clock on the water-cooled version of RX Vega is
1677MHz.
Here’s where things start to get a little
wonky. If you want an air-cooled Vega 64 or 56, you’ll be able to buy
those straight. If, on the other hand, you want the liquid-cooled Vega
64, you’ll have to buy it as
part of a bundle. So, for example, the bundle price on the Vega 64 LC is
$699 — but for that $699, you get a coupon for $200 off a Samsung CF791
34-inch WQHD Curved FreeSync monitor, a $100 discount on a Ryzen 7 CPU +
motherboard bundle, and two free games (Wolfenstein II and Prey in
North America).
I’m not sure this bundle idea is the best way
to move product. Don’t get me wrong; $300 in coupons for quality
hardware is a worthwhile bonus, as are the two solid games — but only if
you were already planning to build a new system in the first place.
That Ryzen 7 CPU + motherboard bundle is still going to cost you over
$200, and even the sale price on the CF791 is $749. If you’re planning
to drop serious cash on a new
rig, these offers are helpful. Otherwise, not so much. In fact, I think
AMD knows it, and has deliberately made the liquid-cooled Vega a
bundle-only part precisely because it knows it either can’t sell enough
cards at that price to make any money or because they’re only planning a
very limited run in the first place.
What About Performance?
Performance is… not what people were hoping
for. AMD didn’t reveal a lot of details, but they mainly focused on
emphasizing minimum frame rates and overall frame rate smoothness. Both
of these are good qualities for a chip, but people expected RX Vega to
be some kind of super GTX 1080 Ti killer. And… well, it isn’t. AMD has
stated that they expect the RX Vega to trade blows with the GTX 1080,
and the overall pricing reflects that expectation. So here’s how this
breaks down:
RX Vega 56:
1156MHz base clock, 1471MHz boost, 64 ROPs, 224 texture units, 3584
shader cores, 2048-bit memory bus, 410GB/s memory bandwidth, 8GB of
HBM2, and a 210W TDP.
RX Vega 64 (Air):
1247MHz base clock, 1546MHz Boost, 64 ROPS, 256 texture units, 4096
shader cores, 2048-bit memory bus, 484GB/s of memory bandwidth, and a
TDP of 295W.
RX Vega 64 (Water):
1406MHz base clock, 1677MHz boost clock, 64 ROPs, 256 texture units,
4096 shader cores, 2048-bit memory bus, 484GB/s of memory bandwidth, and
a 345W TDP.
From this point forward, air-cooled and water-cooled will be referred to as AC and WC for the sake of my sanity.
As always, we’ll hold on final judgment until
we have shipping, tested silicon, but these are not the kind of figures
people were hoping for. The GTX 1080 Ti has a TDP of 250W. Anyone who
says “TDP doesn’t equal power consumption” is absolutely, 100 percent
right, but TDP ratings tend to at least point in the general direction
of power consumption, and a rating of 295W for the AC Vega and 345W for
the WC version tells us a lot about how these chips handle clock rates.
Consider: The RX Vega 64 AC is clocked 8
percent higher (base) and 5 percent higher (boost) than the RX Vega 56,
and has 15 percent more cores. Yet the TDP difference between the two
chips is enormous, with Vega 64 AC drawing 1.4x more power than Vega 56.
Now, as we’ve often discussed before, power consumption in GPUs isn’t
linear — it grows at the square or cube of the voltage increase, and
clock speed or memory clock increases will only make that worse.
Being able to compare with RX Vega 64 LC makes
the problem a bit easier to see. The AC and LC variants of Vega only
differ in clock speeds. RX Vega LC’s base clock is 1.13x higher than
Vega AC, with a boost clock gain of 1.08x. But those gains come at the
cost of an additional 1.17x TDP. In other words, at these frequencies,
Vega’s power consumption curve is now rising faster than its clock
speeds are.
We’re not preemptively calling this Nvidia’s
game, not by a long shot. But AMD’s pricing, bundle, and overall part
positioning seem to imply the RX Vega 56 will compete against the GTX
1070 while the Vega 64 competes against the GTX 1080. And if you care
about power consumption, unless AMD has some crazy last minute
optimizations up their sleeve, we’ll be watching the company’s new GPU
face off with Nvidia’s May 2016 flagship, not the more recently launched
GTX 1080 Ti.
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