Newsgroup: it.comp.hardware.video-3d
Titolo: Riva TNT, la nVidia si ripete

Pare che, come accadde per il Riva 128 (che quando uscì andava bene,
sì, ma era veloce la metà di quanto decantavano le specifiche), anche
il TNT non sia all'altezza di quanto promesso.
Ho preso da 
http://www.ve3d.net/3Fingers/3D_OverTime/
 questo interes-
 sante articolo:
Is the TNT as Dyn-o-mite as Advertised? 
In a nutshell: Nvidia’s hotly anticipated Riva TNT chip appears to be
having some birthing pains. A scant two months before the planned
release of this premier 2D/3D "Voodoo 2 Killer" chip, the only
benchmarks available fall far short of paper specifications. These
benchmarks, released two days ago by nVidia themselves (not an
independent source), show Voodoo 2-level performance where there
should be around 2-3x that much. Between nVidia’s likely financial
troubles and the apparent performance shortfall of the chip, the
company and the TNT could be in serious trouble. 
What is it? The Riva TNT is nVidia’s upcoming 2D/3D super-chip. This
part is supposed to wipe the floor with the Voodoo 2, and, for that
matter, everything else due out this year. On paper, this chip looks
amazing: it’s designed to peak at 250 million single-textured pixels,
or 125 million dual-textured pixels per second (compared to 90 million
in either case for the Voodoo 2), with excellent visual quality and
nifty features like full-screen dealiasing. This is nVidia’s hope for
the future, and it’s bid to take the pole position in the 3D race.
It’s also been the darling of the media and the fear in the heart of
many a stockholder in Videologic (PowerVR) and 3Dfx (Voodoo). It’s
probably reasonable to say that the future of the 3D industry will be
strongly affected by the TNT, whether it succeeds or fails. 
As one might expect, people have been waiting anxiously for months now
to get their hands on some concrete performance numbers (let alone
demo boards). There were developer’s events on June 11th and 25th
("Direct3D Summer Camp") cosponsored by Microsoft and nVidia at
which the participants were supposed to receive a prerelease TNT
board, but the production run was "delayed" and attendees were shown
demos instead. In addition to these developers, a number of people
have also seen controlled, behind-doors demonstrations from nVidia,
but even in those cases, few games have been shown, apparently, and no
one has been allowed to obtain frame rates (fps). Most of us,
meanwhile, have been left only with the paper specs and with press
releases that say things like, "the TNT runs Quake 2 at 1600 x 1200 at
reasonable frame rates." Whatever that means. 
So you can imagine that the release, two days ago, of some performance
figures on two benchmarks (Turok, and Winbench 3D) caught a lot
people’s attention. The purpose of this article is to reexamine what’s
publicly known about the TNT in light of those figures, and in
light of the chip’s imminent release date (the company claims August).
However, in order to evaluate what nVidia is telling us (via these
benchmarks) that the TNT can currently do, we need to know what it was
designed to achieve: we need to review the chip’s much-publicized
specs. 
The Specs: The Riva TNT boasts an amazing set of specifications - it
sparkles on paper. For comparison purposes, I am presenting these
specs alongside those for the Voodoo 2, in both single and dual board
(SLI) configurations. 
                              Chip Specifications 
Riva TNT   Voodoo 2            Voodoo 2 SLI
Max triangles/s (setup)
8 million       4 million               4 million
Max single-textured Pixels/s 
250 million 90 million           180 million
Max dual-textured Pixels/s 
125 million  90 million          180 million
Chip clock speed
125 MHz     90 MHz               90 MHz
Max bandwidth
TNT: 3.2 GB/s (200 MHz memory)*
Voodoo2: 2.16 GB/s
V2 SLI: 4.32 GB/s
Max resolution (dbl buffer)
TNT: 1600x1200
V2: 800x600
V2 SLI: 1024 x 768
Internal color accuracy
Tutti e tre: 24/32-bit
TNT Special features
- Anisotropic filtering (4x speed penalty) 
- uses up to 200 MHz SGRAM 
- AGP 2X 
- full-scene anti-aliasing (4-8x speed penalty?) 
- stencil buffer 
- 2D capability 
 
Voodoo2 Special features:
Dual-board SLI
[* "GB" here is approximate: 1,000,000,000 is treated as one GB rather
than the actual 10243
=1,073,741,824.] 
Most impressive! So what do these specs imply in terms of performance?
First, that, CPU willing, the TNT should run single textured
applications (e.g. Turok, Forsaken, etc.) almost 3x faster than a
single Voodoo 2 (250 million/90 million pixels/s), and 1.4x faster
than Voodoo 2 SLI. Second, that, likewise, the TNT should run
multi-textured applications (e.g. Quake, Quake 2, etc.) about 1.4x
faster than a single Voodoo 2 (125 million/90 million pixels/s), and
0.7x as fast as Voodoo 2 SLI. It should do all this while providing 2D
as well as advanced rendering options, yet! Basically, the TNT should
roundly kick Voodoo 2’s butt. 
So, does it?: Let’s examine the benchmark figures provided by nVidia
to Cyrellis 3D with these specs in mind. The numbers that nVidia is
apparently getting (on a PII 400) are as
follows: 
                              nVidia's Numbers 
Riva TNT (16 MB prototype)     Voodoo 2 (single 12 MB board)
Turok
         88.5 fps                                          79.0 fps
 Winbench 3D
          1280                                             1260
Hmmm. This is impressive in the sense that this is the first
relatively credible demonstration of a 3D card exceeding Voodoo 2
performance (S3’s reported Voodoo 2 Turok framerates are
suspiciously dramatically lower than those obtained by independent
testers). In fact, this is the spin put on these results by the
generally positive Cyrellis article. However, I hope and suspect
that you are now thinking what I thought on seeing these values: "Huh?
That’s too slow!"
Remember, the TNT should whup the Voodoo 2’s hiney on single-texture
games, like Turok, by nearly a factor of 3, not 1.1! Something’s odd
in 3D-land. 
Since Winbench 3D is poorly related to gaming performance and
notoriously easy to influence via "creative" driver design, let’s
focus on the Turok numbers. In order to do this, however, we
need to know several things that the Cyrellis article doesn’t provide:
what resolution is the benchmark running at, and what are some
independent results for similar systems. Fortunately, we can obtain
both pieces of information, directly or indirectly, from the Turok
benchmark results gathered by the well-respected Tom Pabst of Tom's
Hardware. There’s more that we’d like to know, of course, such as
which rendering options were enabled during benchmarking,
but we’ll have to make do with what we’ve got. 
                               Tom's Numbers 
 Voodoo 2 (one 12 MB)                 Voodoo 2 SLI (two 12 MB)
  Turok (640 x 480)
       93 fps                                                 122 fps
  Turok (800 x 600)
       62 fps                                              106.5 fps
Looking at these numbers, a few things pop out right away. First, the
resolution of the nVidia benchmark runs was almost certainly 640 x
480, since the Voodoo 2 seems to be unable to go faster than 62 fps at
800 x 600. Second, the Voodoo 2 can apparently do a lot better on
Turok than nVidia’s reported results would indicate. Moreover, 93 fps
is not only better than the 79 nvidia got for the Voodoo 2, it is
actually better than the results they reported for the TNT (88.5)! 
This raises the question: why is Tom’s result different from the
nVidia result? Well, it could be that Tom has been leading us on, but
he not only has little reason to do so, he is also under fairly close
scrutiny by a community full of people capable of running the same
benchmarks: I’m quite inclined to trust his numbers. Could Tom’s
results have come from the higher-performing Glide version of Turok?
Almost certainly not - not only were these results part of a general
comparison with other chips that can’t run the Glide version, but
Tom’s earlier D3D-based Turok numbers on a PII 300 (77.5 fps) are
quite in-line with his PII 400 values. Most likely, the difference
either lies in game/card setting differences (e.g. refresh rate, sound
on or off, etc.), or there is some funny business going on. After all,
while it’s hard to believe that nVidia didn’t run the TNT in the most
framerate-advantageous manner they could come up with, it's rather
easy to imagine that they didn’t work quite as hard to get the most
out of the Voodoo 2 :-). 
Either way, there are more oddities in the mix. First off, why didn’t
the TNT do better? If we assume that nVidia ran the TNT in the most
advantageous way possible, then the numbers from Tom’s site indicate
that the Voodoo 2 is currently faster than the TNT! One theory that
comes to mind is that the TNT is CPU-limited at 88.5 fps: however,
this isn't possible since Tom’s Voodoo 2 SLI rig, which should be
slower than the TNT, produced 122 fps. In fact, it’s pretty hard to
escape the conclusion that the TNT and its driver should have topped
out at 122 fps due to CPU limitation; a value, mind you, still far
below the chip’s theoretical peak of roughly 250 fps. 
Apparently, according to the Cyrellis article, nVidia is laying the
blame on their drivers, claiming that they are "at ‘50%’ of their
final form." That’s a nearly meaningless statement as far as I’m
concerned: does it mean 50% done? 50% of final speed? I suspect that
nVidia wants to imply the later without getting caught in an explicit
claim. Either way, it’s pretty hard to swallow - aside from the fact
that the TNT appears to be performing at more like 35% of it’s
paper performance, drivers seldom (if ever) improve anywhere near that
much (150-200%) over the last two months of a chip’s development
cycle. Given the mysterious delay of the developer’s pre-release
cards, and the general lack of benchmarks and sample boards, I find it
more credible that the chip isn’t performing up to snuff and that they
are scrambling to put the best spin on it they can. 
Another reason to doubt the "driver" theory is that they apparently
run the benchmark at 640x480. Since driver inefficiencies shouldn’t
curtail fillrate once a triangle gets to the board, if the driver is,
in fact, the problem, then we should expect that the TNT has fillrate
to burn (and then some) and should perform just as well at 800 x 600
as at lower resolutions. If that is true, then the most advantageous
comparison for nVidia would have been at 800 x 600, not 640 x 480:
why pit the TNT’s 88.5 fps against the Voodoo 2’s 93(79) fps low-res
figure, rather than the Voodoo 2’s 62 fps (or whatever lower figure
nVidia would get :-) high-res one? Basically, if the driver is the
problem, then the TNT should be just as fast at the higher resolution,
while the Voodoo 2 would slow down, being fillrate-limited: the
comparison should therefore look much better for the TNT at 800 x 600.
Yet nVidia chose to release their first public numbers using 640 x
480… are the people there dense? I sincerely doubt it. It seems much
more likely that the TNT’s problems are deeper than a simple driver
issue. 
In fact, things look even worse when you consider some of the other
conditions in this comparison which favor the TNT.  For example, the
TNT uses AGP 2x, which should be about 4x faster than the PCI bus used
by the Voodoo 2. The TNT also has much more texture memory available
than the Voodoo 2 does. Add to that the fact that the Voodoo 2 could
have been run at up to 100 MHz (11% more peak performance), and could
have been tested with the Glide version of Turok (about 10-15%
faster), and the TNT’s failure to smoke the Voodoo 2, much less even
match it according to Tom’s numbers, looks pretty bad. 
So, what’s you’re theory, then?: In my opinion, nVidia is having
problems finishing and performance-debugging the chip due to some
combination of the following: financial difficulties arising from
price pressure on their cash cow (the Riva 128), financial
difficulties arising from the apparently indefinite delay of their
IPO, unforeseen design issues, overcomplexity of the part (at 7
million transistors), difficulties getting the chip’s two texture
pipelines to operate in parallel (producing two single-textured pixels
per cycle), or something else :-). Interestingly, even if the chip
were performing up to spec, the inavailability of 200 MHz SGRAM would
slow things down. However, the slow down from using available 125
MHz memory would be nowhere as severe as the benchmarks discussed
above would indicate. Basically, I think nVidia is having problems
with the TNT’s hardware, and that they had better either get cracking
or announce a delay in the product’s release, since current
performance, as measured by these benchmarks, is unlikely to gain them
significant market share - especially after months of hype and
sky-high expectations. 
The Bottom Line: Nvidia’s current boards, the Riva 128 family, fell
short of predicted performance by as much as 50%. The TNT may well
follow suit. The current evidence - "delayed" developer boards, PR
without framerates, only Voodoo 2-level performance on the one game
they chose to release numbers for, the use of low-resolution for that
benchmark, etc. - points pretty strongly towards two possibilities:
either the TNT will be late, or it will be much slower than expected.
Neither case would be a happy result for nVidia, which has a lot
(quite possibly its survival as an independent company) riding on the
TNT’s success. If the board is late, then their OEM partners may
desert them, and they may experience severe cash-flow
problems. If it is little or no faster than a Voodoo 2, people will
scoff at it for its failed pretentions and will buy the much cheaper
2D/3D boards from other vendors (e.g. the G200, Banshee, PVRSG, etc.).
Unlike the relatively cheap Riva 128, the TNT will be a high-priced
part which cannot afford to fall far short of its specifications. 
Frankly, in my opinion, the numbers they released paint a rather grim
picture for nVidia. Hopefully for them, and for the consumers eager
for the high-performance the company has promised, nVidia will pull
the proverbial fat out of the fire: after all, the story is hardly
over.
However, it is getting close to the moment of truth and it’s beginning
to look like the happy ending may evaporate into a who-dunnit murder
mystery. 

...


>>>   
fea...@tin.it
   <<<<
cin...@iperbole.bologna.it

in versione alpha.
E perchè nVidia non lo ha detto? Le sarebbe convenuto farlo presente:
"guardate, questi sono i risultati dei nostri confronti col Voodoo2.
D'accordo, le nostre specifiche su carta promettevano una velocità
quattro volte superiore, ma considerate che la scheda andava ad un
clock dimezzato e che i driver sono incompleti". Se fosse andata così,
non staremmo a parlarne.
Invece no. Tralasciando il fatto che i risultati di riferimento del
Voodoo2  postati da nVidia sono molto più bassi di quello che
normalmente si ottiene con una Voodoo2, tralasciando il fatto che
contrariamente a quanto promesso ai vari sviluppatori non è stata
consegnata una scheda che sia una - in barba a 6/8 mesi di annunci
mirabolanti, PR trionfalistiche eccetera -, tutto quello che nVidia ha
detto è "I driver sono al 50%". Qualunque cosa ciò significhi.

detto è "I driver sono al 50%". Qualunque cosa ciò significhi.
Posso solo dire che chattando con Paolo Corsini  ho afferrato (mi pare
proprio di aver capito bene, lui comunque la sa molto lunga)
che anche la TNT sara' una delusione.
Gigi

che anche la TNT sara' una delusione.
Adesso non passiamo da un estremo all'altro, su. :-)
Secondo me non sarà quello che è stato promesso (un 3D tre-quattro
volte più veloce del  Voodoo2, il 2D più veloce del mondo, il tutto in
un solo chip venduto a 3-400mila lire a utente finale); ma sarà
comunque un'ottima scheda, complessivamente.

Adesso non passiamo da un estremo all'altro, su. :-)
..volevo solo dire che, a dispetto dell' 'hype'
publicitario, molto probabilmente (sempre secondo
la sopracitata fonte) anch'essa sara' inferiore o
uguale alla voodoo2, quando si verra' allo
show down, circa i benchmark nudi e crudi  dei giochi.
Gigi

quasi sempre più lento di una V2.
Puo' essere, ma aspettiamo di vederlo, cosi' come per il Tnt.

Puo' essere, ma aspettiamo di vederlo, cosi' come per il Tnt.
Hai ragione anche tu.... ma stavolta è un'ammissione della 3dfx stessa, e
del resto basta vedere com'è costruito Banshee per capire la situazione.
Semmai potrebbe vedersi qualcosa di migliore col piccolo redesign previsto
per pochi mesi dopo l'uscita: ne avrai sentito parlare, transistor più
piccoli, maggior frequenza di clock e (per quel che conta) AGP 2X. Forse
quella scheda potrà tornare sui livelli della V2, anche se ho dei dubbi.




stavolta.
Oh, si, non c'e' dubbio. D'altro canto dovremmo esserci abituati,
basta guardare la pubblicita' del bianco che piu' bianco non si puo',
delle brioches grondanti di marmellata (che poi si riduce a una
striscia minuscola al centro), ecc. Chi vuole vendere cerca come
minimo di mettere il proprio prodotto nella luce migliore.