copyright 1998-1999, Alison Hine
http://simracing.com/alison/gpl/faq-hw.htm
Many people have asked me about what sort of computer they need to run
GPL well, and whether or not the computer they have now is up to the
task. Here's a compendium of the best information I have right now about
this topic.
1.1 What frame rate should I get in GPL?
After a lot of experimenting, I consider it essential to get 36 fps
(there is a handy frame rate counter in the final version).
I know that humans are not supposed to be able to see anything more than
30 fps, but when my machine is running at 30 fps, the action seems
choppy and I can't control the car as well. By the time I've seen what
it is doing and react, it has gone too far, so my corrections tend to be
late and not enough. This leads to PIO (Pilot Induced Oscillations),
slow lap times, and crashes.
You may be different, but I've found that I drive much better when my
machine is running at a steady 36 fps.
1.2 I have a Pentium Classic and 128 mb of memory. When I run GPL, about
one in ten times it runs ok, but the rest of the time, frame rate is
terrible, about 2 fps.
This is most likely due to a problem with many Pentium Classic
motherboards. Although not all boards have this problem, there are many
which do not cache memory above 64 mb. This means that if GPL loads into
high memory, it will not be able to use L2 cache, and performance will
be dreadful.
The workaround is to remove all but 64 mb of the memory in your machine.
If GPL now runs fine, this was the problem. I am not aware of any fix;
you'll need to upgrade your motherboard if you want to run with more
than 64 mb of memory.
2.1 How fast a CPU do I need?
Papyrus says that the minimum platform for GPL is a P-166, and I agree
with this. I had a P-166 and it ran ok on that machine. However, you
need at least 256k of L2 cache, and (IMHO) a Rendition 2x00 card to get
decent frame rate on any Pentium Classic. You will also have to turn
down a lot of graphic detail if you want to run with any AI cars, or in
multiplayer mode, and you won't want to have more than 5 other cars on
the track even if you've turned the detail way down.
I eventually upgraded my P-166 to an AMD K6-200, which I overclocked to
75x3 so it is running at 225. More importantly, it is running the L2
cache, which GPL uses heavily, at 75 mhz instead of 66 mhz, and this
helps a lot. I also installed an 8 mb Hercules Thriller, replacing the
Sierra Screamin' 3D which was in it originally.
This machine is much better now, and can run 5 AI cars with a fair
amount of graphics detail at 640x480, or about a dozen AI cars with all
but what I consider essential graphics detail turned off. It's fairly
good for multiplayer play; I've tried it with up to 4 opponents, and as
long as I turn off enough detail it works fine.
Papyrus says that the preferred machine is a Pentium II, at least 266
mhz. I heartily agree with this. In the past few days, I put together a
PII-350 with 128 mb of PC-100 memory and an 8 mb AGP Hercules Thriller.
It is awesome. I get a solid 36 fps at 800x600, all graphics details
turned on, and 19 AI cars. When I enter the pits, it's about 24 fps, but
by the time I've passed the last AI car sitting in pit lane, it's at 36
fps and stays there.
2.2 Is L2 cache essential for GPL?
On Pentium Classics, yes. GPL is very memory intensive, and without L2
cache, it simply will not be able to perform its tasks efficiently. If
it runs at all, GPL's frame rate is likely to be very poor.
The situation is different for Celerons. See below.
2.3 How do I find out if I have L2 cache?
One to find out if you have L2 cache is to watch the BIOS screen when
the machine is booting. Most BIOSes will report the cache that is
present in the machine on the box of information which appears
momentarily during the boot process, before Windows 95 starts to load.
On my machine, the Cache field is in the lower right-hand corner.
Another way is to check the manual for the motherboard, which should
have come with the computer. If it's an older Pentium Classic, it may
not have any L2 cache, but if the motherboard was made after 1996, it
most likely will. Depending on how complete the manual is, you may have
to open the case to look for the L2 chips; the manual should at least
show where the chips are located if they are present.
2.4 I have a Celeron. I can overclock it to 448MHz if I need to, by
running the bus at 112. Am I likely to have major problems due to lack
of L2 cache?
No, GPL seems to run well on Celerons despite the lack of L2 cache,
especially if you overclock the Celeron.
The only issue seems to be when hosting Internet-based multiplayer races
over a DUN connection. The resulting frequent interrupts by the serial
port apparently blows out the L1 cache, making the CPU work harder.
This can impact online play because when the host's CPU gets busy (i.e.
it's generating less than 36 fps), gameplay on the client machines is
degraded. The frame flow on the client machines can get choppy (called
"frame stuttering") even if the client's CPU is not overloaded. The
workaround is to cut back on graphics details on the host till frame
flow smooths out on the clients.
If you're not hosting multiplayer races online, this won't impact you at
all and the Celeron should be fine.
See my GPL Online FAQ for detailed information about regarding online
racing and related issues.
2.5 What about an AMD K6-2? Will that run GPL as well as a Pentium II?
I have no experience with the K6-2, although I have run GPL for months
on a K6-200 overclocked to 75 x 2 = 225. This processor worked very
well, and its superior performance in comparison to my P-233 suggests
that the FPU superiority of the Pentium over the AMD K6 was not as
important as running the L2 cache at a higher speed.
However, the architecture of the new Super 7 motherboards makes it
impossible to run the K6-2's L2 cache as fast as a Pentim II runs its
on-die L2 cache, and benchmarks at Tom's Hardware Guide suggest that a
K6-2 will underperform a Pentium II running at the same clock rate by
perhaps 5 to 10%.
GPL does not currently have any way to take advantage of the K6-2's
3DNow! parallel FP unit, although if Papyrus were to release an OpenGL
driver for GPL, this could change.
Still, cost considerations may make the K6-2 a viable alternative to a
Pentium II setup for a high-performance platform for running GPL.
2.6 If I go with a K6-2, will I have an upgrade path for the future?
On the horizon are several interesting new K6/Socket 7 processors from
AMD. The first is the K6-2-400, which should be available shortly.
Compared with the earlier K6-2's, the 400 features improved internal
architecture which should give performance close to or equal to that of
a Pentium II running at the same clock speed.
Experience with GPL running on L2 cacheless Celerons suggests that at
CPU clock speeds of 400 and above, L2 cache becomes less important.
Therefore, a Super 7 motherboard, PC-100 memory, and a 400 mhz K6-2
seems likely to be an excellent setup for running GPL.
Even more interesting is the upcoming K6-3, or "Sharptooth", due out in
late 1998 or early 1999. The K6-3 features on-die L2 cache, like the
Celeron 300 A and 333, but running at full CPU clock speed. Thomas Pabst
of Tom's Hardware Guide believes that this will allow the K6-3 to
outperform a Pentium II running at the same clock speed, and I would
guess that he's right.
The K6-3 will be available at up to 450 mhz, and will go right into a
Super 7 motherboard, providing an upgrade path for those who go with a
K6-2 before the release of the K6-3.
My guess is that a K6-3 at 400 or above would be a superb platform for
GPL. I wouldn't be surprised if a K6-3/Super 7 combo finds its way into
one of my older machines sometime soon.
2.7 What's after that from AMD?
By mid 1999, AMD expects to release the K7, which will go into a new
type of motherboard known as "Slot A". Based on Digital's Alpha
technology, the Slot A bus will be significantly superior to the Pentium
II's Slot One. The K7 will be able to support much larger L1 and L2
cache on die than the Pentium II, and is also expected to have a
superior FPU and run at very high CPU clock speeds. A number of other
innovative features should make it blindingly fast compared with
anything available today.
For GPL, which runs quite well on a PII-400 with every option turned on,
a K7 would probably be overkill, but it will be interesting nonetheless.
3.1 Can I run GPL if I don't have a Rendition or Voodoo card?
Yes. There is a software-only rasterizer which will work with any 2D or
3D card.
3.2 Will GPL run well in software-only mode?
No. There simply aren't any machines that are fast enough yet to do
everything that GPL needs in CPU, and do it well enough to run GPL at
anywhere near its best. If you have a PII-450, and you turn off most or
all of the graphics details, you may get decent frame rate.
Suitable 3D cards are so cheap and so powerful these days, it simply
doesn't make sense to try to play GPL without one. You can do it, but
you will not experience the game in anything like its true splendor, you
will probaly not enjoy it very much, and you will be wasting your time,
IMHO.
3.3 Ok, so what 3D accelerator should I buy?
There are a lot of Voodoo cards out there, and a lot of fans of Voodoo
cards. Magazine reviews and benchmarks seem to show that the Voodoo 2
far outperforms any other video card, hands down.
But. The benchmarkers are running games which are optimized for the 3Dfx
architecture. GPL, which is also optimized for the Rendition
architecture, is a very different story.
The 3Dfx architecture has great fill rate, but the Rendition
architecture is superior in several other ways. According to sources
within Papyrus, the most important for GPL is that, unlike the Voodoo,
Rendition cards do not distinguish
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