Official XS 7950GX2 Guide - Your Questions Answered

[Turok]

***Official XS 7950GX2 Guide***






Introduction:
The purpose of this guide is to answer all the questions about the new 7950GX2 that have been showing up in XS.
If you're planning on updateing to a single 7950GX2 or Quad-SLI, or you currently own one, this thread is for you.

Pros & Cons of a 7950gx2:
Pros
1) A single 7950gx2 is faster and its clocked lower than each 7900GT
2) Some 7900GT still have defective capacitors AFAIK, which causes the card to die in a short time.
3) A single 7950gx2 can run in about any board with a PCI-E slot (but check for compatibility just to be safe)
4) The vGPU is between that of 7900GT and GTX, but the vMem is lower than both the 7900GT and GTX
5) 7950gx2 is more like an underclocked 7900GTX than a pair of 7900GT.
6) Considering #4 & 5, the 7950gx2 has a good chance of easily reaching 2x 7900GTX SLI speeds with the proper cooling.
7) You can run Quad-SLI and crank up AA to 32x
8) A single 7950GX2 uses less power than a single x1900xt, and Quad-SLI 7950GX2 uses less power than a x1900xt CF setup.

Cons
1) The space between the cards is verry narrow, which makes it hard to put a better cooling solution.
2) The card was built to use low voltage, so you will need to volt mod it for Xtreme OCing.
3) Quad-SLI drivers are a bit immature atm
4) Quad-SLI makes a huge CPU bottleneck
5) I noticed some IQ defects on my Source engine games that were also visible in a few ATi vs nVidia IQ comparisons when the 7 series was first released, but Leviathan18 says he didnt see it with his 7800GT and 2x6600 GT. Im guessing its probably a temporary issue with the nVidia drivers, because the early 6 and 7 series cards had it but the problem was fixed


A few answers to some questions:
- The 7950GX2 runs about the same as 2x 7900GT on SLI on power consumption
- The inner card runs about 10 degrees C hotter than the outer card
- The SLI controller is on the inner card, and it can run fine with a passive chipset cooler
- All the data exchanged from the PCI-E slot goes through the card's SLI controller first
- You dont need 16x SLI to run Quad-SLI, but it will probably give you a bit of a performance gain


Recommended setup for Quad-SLI:
Even if you have Quad-SLI and good drivers, it doesnt mean you have the fastest GPU solution to date.
If you dont stress your cards enough, the performace will be even worse than 2x 7900GT.
Make sure your're running at GPU dependent settings above 1600x1200 with high filtering and max settings on current games.
However, In the future when Unreal Engine 3 and Crysis based games release you wont need to

Stressing your GPU isnt enough to avoid CPU Bottlenecking, tho.
You also need the hardware to process all that load at high resolutions:
Minimal specs for Quad-SLI:
- CPU: AM2 2.8Ghz or Conroe from 2.1Ghz to 3Ghz
- Mobo: nForce 590 or Intel 975x (w/ SLI hack) based mobo
- Mem: 2x 512mb DDR2 633Mhz CL 3
- PSU: OCZ GameXstream 600w, PCP&C Silencer 610 EPS12V, or simmilar

Recommended specs for Quad-SLI:
- CPU: AM2 >3.4Ghz or Conroe >3Ghz
- Mobo: Best nForce 590 or Intel 975x (w/ SLI hack) based mobo
- Mem: 2x 1Gb DDR2 1000Mhz CL 5
- PSU: PCP&C Silencer 750 EPS12V, PCP&C Turbo-Cool 850 SSI, or simmilar


Recommended Brands:
This question gets asked a lot of times, especially by people who never used a nVidia card before.
The best companies atm for a 7950GX2 are:
- eVGA
- XFX
- BFG

MSI is also good, but the 3 mentioned above have a
good reputation in overclocking and product quality


Cheap places to buy:
USA:
ZipZoomFly
eVGA 7950GX2 600/1200Mhz + HL2 + Free Shipping = $539.99

NewEgg -->All 7950GX2
eVGA 7950GX2 500/1200Mhz + Hitman = $526.12
MSI 7950GX2 500/1200Mhz + $30 MIR = $507.12

UK:
?

EU:
?


Drivers & Mobo Support:

Current ForceWare Drivers:
ForceWare 91.31 -> Current official release
ForceWare 91.33 Beta -> Try 91.33 if 91.31 and 91.45 isnt working properly
ForceWare 91.45 Beta -> best for Quad-SLI. Lets you make custom Quad-SLI profiles

nVidia's list of 7950gx2 mobo compatibility:
http://www.nvidia.com/content/geforce_gx2_sbios/us.asp

Quad-SLI on ANY chipset:
To run SLI on any chipset, you need this hacked ForceWare driver:
http://www.xtremesystems.org/forums/...d.php?t=106212
It lets you run SLI even on Intel and ATi based chipsets


Watercooling your 7950gx2:
People who are planning on running OCed Quad-SLI may need to update to waterblocks. Current watercooling solutions for the 7950GX2 dont perform as well, and are a bit expensive.
in this thread we discuss a bit about custom 7950GX2 blocks:
http://www.xtremesystems.org/forums/...d.php?t=104693
Unfortunately the thread eventually died and got pushed back in the Water Cooling section
But the thread is still useful if you want some inspiration on block building.
You could also try reviving the thread to see if someone can build you a block, or you could try build your own if you have a CNC machine and you can post there so everyone can see it

For anyone who is interrested, I made some detailed sketches of my 7950GX2:
I posted these measurements on the thread above, and you can use them as reference for block building.
The sketch shows a precise layout of all the chip locations, and each measurement is shown in both mm/cm and inches.
If you have any questions about the drawing, feel free to ask



Makeing your 7950GX2 wider:

The exact spaceing on a 7950GX2 from board to board is 1.6cm.
With double the spaceing you can easily fit the top 3 GPU blocks:
The DD Maze 4, the AX MP-1 and the Swiftech MCW60




This is the best solution so far:




Swiftech's GX2 Spacer kit for $19.95
It doubles the space between the cards.
the kit includes the following:
# 3 Male-Female 4-40 standoffs
# 1 Female-female pass-thru standoff
# 1 Female-Female 4-40 standoff
# 1 4-40 philips screw
# 1 MC14 Ramsink (for the SLI switch chip)
# 1 extended PCB.

Ramsink is sold separately.

Link:
http://www.swiftnets.com/products/7950GX2Spacerkit.asp

Volt Modding your 7950gx2:
Shamino made a nice volt mod guide at VR-Zone:
Try it at your own risk
http://www.vr-zone.com/?i=3659

BIOS Mod for your 7950gx2:
-=Merlin=- has a thread in the "Xtreme mods > Xtreme Graphx Vmods" section called "7950GX2 Bios Mod" where he's modding several 7950GX2 BIOS to run the fans at full load.
This is useful for benchmarking for those with stock cooler.
http://www.xtremesystems.org/forums/...d.php?t=113377

Stuff that could be added if this sticky becomes more popular:
* OCing results from other threads in XS:
* Reviews and Benchmarks from other sites:
* Info about 7900GX2:
- The first Quad-SLI card that measures like 30cm long

In the future the thread title could be changed to a thread dedicated to Quad-GPU solutions, since there are rumors that nVidia's top G80 card will be a Dual-GPU single card solution like the 7900GX2 and 7950GX2

At the moment I also have to update my LCD Guide which is pretty out dated.
If people can help me with info, reviews, terms, and new upcomming tech, then I could link the LCD Guide to this thread too for people who are interrested in HD gaming with their new Quad-SLI setup and a LCD greater than 1600x1200 resolutions. Even if the buyer is considering a CRT, the guide has some useful info that's true on all monitors.
http://www.xtremesystems.org/forums/...ad.php?t=71226