To SLI or not?

  • Thread starter Thread starter Fitz
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Fitz

Considering a computer upgrade from an AMD64 754 pin system (AGP) to a
AMD64 X2 4800. Is SLI stable enough and offer
enough of a performance boost to justify 2 512MB 7950's, or would one
1GB 7950 offer about the same performance (or more stability)?

The motherboard would be an ASUS A8N 32 SLI Delux, unless anyone has a
better options to offer.

Fitz
 
Fitz said:
Considering a computer upgrade from an AMD64 754 pin system (AGP) to a
AMD64 X2 4800. Is SLI stable enough and offer
enough of a performance boost to justify 2 512MB 7950's, or would one
1GB 7950 offer about the same performance (or more stability)?

The motherboard would be an ASUS A8N 32 SLI Delux, unless anyone has a
better options to offer.

Fitz
Click to expand...

Try one card. If it isn't fast enough, buy a second card :-)

If you look on places like Anandtech, they typically mention
the use of SLI for people with high resolution/large monitors.
If you play at 1024x768 or 1280x1024, you may be happy with
just the one card. If you use a monitor with larger resolutions
than that, then SLI might be for you.

http://techreport.com/etc/2005q3/hires-gaming/index.x?pg=1

AFAIK, these SLI/Crossfire technologies, continue to be limited
to a single monitor. There is a Matrox gadget, that will take
one VGA output, and drive two or three monitors with it. You
can take a 3840x1024 video output, and drive three monitors
at 1280x1024. That is one way to get SLI driving multiple
screens - assuming the game will run video output in a mode
like that.

http://www.anandtech.com/showdoc.aspx?i=2806&p=1

Paul
 
Try one card. If it isn't fast enough, buy a second card :-)<

Thought of that until I looked at the cards....the 1GB 7950's appear to
take up 2 slots,
and I don't think there would be room on the board to run 2 cards @ 2
slots each along
with a couple of standard PCI devices. That's why I'm trying to choose
between 2 512MB
cards (1 slot ea.) or one 1GB card. Can't find any documentation stating
whether or not
the motherboard can accept 2 two slot cards.

Using a Samsung 204B (20 in.) LCD in DVI mode (1200X1600 capable, but I
don't run the
desktop at that).
 
Fitz said:
Thought of that until I looked at the cards....the 1GB 7950's appear to
take up 2 slots,
and I don't think there would be room on the board to run 2 cards @ 2
slots each along
with a couple of standard PCI devices. That's why I'm trying to choose
between 2 512MB
cards (1 slot ea.) or one 1GB card. Can't find any documentation stating
whether or not
the motherboard can accept 2 two slot cards.

Using a Samsung 204B (20 in.) LCD in DVI mode (1200X1600 capable, but I
don't run the
desktop at that).
Click to expand...

Are you referring to a 7950GX2 dual GPU card when you say "1GB card" ?
When I look on Newegg, I only see 7950GT in a 512MB version. I'm not
sure that high quantities of video RAM are that useful, and if a
video card with a single GPU had 1GB on it, it would be a sad waste of
memory bits.

This is what I use as a reference, and this list is not complete.

http://www.techpowerup.com/gpudb/

The memory on cards operating in SLI, do not add. Two 512MB cards in
SLI, gives a grand total of 512MB to the application. On the 7950GX2,
if there was a total of 1GB on the card (512MB per PCB), the grand
total of useful memory when operating in SLI is still 512MB. As I
understand it. (And quad SLI would be doing the same kind of thing -
four copies of the same data.)

http://www.dansdata.com/slibox.htm

"Unfortunately, though, SLI-ed cards can't access each others' RAM,
so texture and other memory-hogging data is duplicated on each card"

7950GT single GPU cards have a higher clock than the GPU on the
7950GX2. Two 7950GT cards with 512MB memory on each, offer 512MB
total memory to the application. A 7950GX2 with 1GB total memory,
offers 512MB total memory to the application. Both solutions are
the same, except the dual 7950GT solution has a slightly higher
clock, and the ventilation of the cards would be "healthier".
On the 7950GX2, I understand one GPU gets hotter than the other.

In the event of a hardware failure (one GPU goes bad), you can
still game by using 7950GT cards. While with the 7950GX2, you'd
have to wait until the warranty replacement arrived.

For high end cards like this, make sure you are covered by a
warranty, for as long as you plan to keep the card. DX10 will
arrive some day soon, so the urge to upgrade again will also
strike soon. Some high end cards have had a 10% failure rate,
so warranty protection and good tech support from the manufacturer,
are important considerations.

Paul
 
Fitz said:
Thought of that until I looked at the cards....the 1GB 7950's appear to
take up 2 slots, and I don't think there would be room on the board to
run 2 cards @ 2 slots each along with a couple of standard PCI
devices. That's why I'm trying to choose between 2 512MB
cards (1 slot ea.) or one 1GB card. Can't find any documentation
stating whether or not the motherboard can accept 2 two slot cards.
Click to expand...

If your mobo has 2 PCIe slots that are far enough apart for the cards
you want to install in them, it can do it. If not, it can't. <g>

SLI/Crossfire have very minimal performance increases over single cards,
according to everything I've read anyway. What "1GB" card are you
referring to? All the cards I saw when looking two weeks ago were 512k.
(I just got the XFX 7950GT 512k that is passively cooled and takes up
only one slot. Had the much faster 7900GTO but returned it b/c I didn't
want the fan.)

Kate
 
Kate said:
SLI/Crossfire have very minimal performance increases over single cards,
according to everything I've read anyway.
Click to expand...

Also, a review I read on "Quad SLI" (2 duals) said it's not worth it, even
if the MoBo can handle it. Apparently the only capable MoBos were initially
released to OEM mfgrs only; none for home building. Of course, that may
have changed with the lag time in the magazines...
 
Thought of that until I looked at the cards....the 1GB 7950's appear to
take up 2 slots,
and I don't think there would be room on the board to run 2 cards @ 2
slots each along
with a couple of standard PCI devices. That's why I'm trying to choose
between 2 512MB
cards (1 slot ea.) or one 1GB card. Can't find any documentation stating
whether or not
the motherboard can accept 2 two slot cards.

Using a Samsung 204B (20 in.) LCD in DVI mode (1200X1600 capable, but I
don't run the
desktop at that).
Click to expand...


I haven't used SLI since 3DFX Voodoo 2 days. Back then I
played games at 640x480 on a 15" monitor. I decided to buy a second
Voodoo 2 to go along with my single Voodoo 2 thinking if I got 60fps
in Quake 2 (Celeron 366), that I would get near a 120fps with SLI.
Well, at the 640x480 resolution I got 84fps. It was good, but not what
I was expecting. I found that SLI enables games to be played at higher
resolutions, with eye candy turned on, and no loss of fps over the
single card.
I'm sure you'd get a performance boost with todays
SLI/Crossfire solutions, but it's problably not what you'd think. It's
more for playing games at extremely high resolutions with AA/AF
cranked up, and all eye candy turned on without taking a performance
hit. If your like me, and game on a 1024x768 resolution, you won't see
much benifit with SLI, since most mid level, single GPU cards don't
break a sweat at that resolution.
As for the 1GB memory. 2 x 512MB cards don't add up to 1GB
total accessed memory. The game still only sees it as 512MB memory,
cause each core has it's own 512MB. It's the same with dual GPU cards
like the 7950 GX2. Like when I bought the dual GPU ATI Rage Fury Maxx
cause the ad said 64MB video memory, but found it was actually like a
32MB card cause each GPU only accessed 32MB.
If you have the cash, and the need for SLI/Crossfire/dual GPU,
then you might be happy with it.
 
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