Go Back   Hardware Canucks > PC BUILDERS & TWEAKERS CORNER > Troubleshooting

LinkBack Thread Tools Display Modes
  #1 (permalink)  
Old February 6, 2007, 04:48 PM
Gav's Avatar
Gav Gav is offline
Join Date: Oct 2006
Location: Canada
Posts: 1,302

My System Specs

Default SLI and CrossFire Push Power Supplies to the Limit

This is a great article from Extremetech if you are having trouble with your computer shutting off while running an SLi or Crossfire setup.

When we were writing our recent socket 939 motherboard mini-roundup, we wanted to test how the system would run with two high-end graphics cards installed. We began with a system that had a Silverstone SST-ST65ZF PSU. This power supply is rated for 650 watts, and is SLI certified by Nvidia. So we fired up an Nforce4 SLI X16 system with two 512MB graphics 7800 GTX graphics cards and an Athlon 64 FX-60. About halfway through the 3DMark06 run, the system shut down. There was no warning, no smoke, no heat. It just turned off. After some grumbling we tried swapping out memory and changing out the CPU. No effect. So we finally switched the power supply to a PC Power & Cooling Turbo-Cool 850 SSI. At that point, it all ran just fine. We were in a rush to wrap up benchmarking the motherboards, so just chalked it up to a bad power supply and moved on.

Note that when the system would shut down, the power supply wasn't even warm—there was no overheating issue there. Later, we replicated the problem with two ATI X1900 cards running in CrossFire mode, so this is not simply an Nvidia issue.

After the article ran, Brett Jacobs from AMD called. Jacobs works in the AMD performance testing lab, which constantly tests dozens of configurations. He had zeroed in on my comment about the system shutting down and had some interesting things to share.

According to Jacobs, AMD had started seeing similar shutdowns with high-end, dual-graphics card setups recently. He was concerned that readers might attribute the problem to the power draw of the FX-60, which would be an incorrect conclusion. Jacobs pointed the finger squarely at dual-graphics cards, noting that the 512MB 7800 GTX can draw in excess of 11 amps when running full bore. If the two cards share a power supply rail, that means that more than 20A is being pulled from one power supply rail, which is a recipe for disaster. According to another source, AMD has started recommending 700W power supplies with high-end SLI or CrossFire setups to alleviate potential problems.

The issue, by the way, has nothing to do with the CPU. AMD was seeing these problems with CPUs as low as the single core Athlon 64 3200+, which draws relatively little power.

More @ Extremetech
Reply With Quote
  #2 (permalink)  
Old February 12, 2007, 03:11 PM
b1lk1's Avatar
Hall Of Fame
Join Date: Feb 2007
Location: Lindsay, Ontario
Posts: 2,769

My System Specs


I had that very same Silverstone PSU and I ran X1800 Crossfire in a heavily overclocked 165 Opteron system and never had any problems at all. I believe they got a bum unit. In my opinion, you just don't need one of those monsterously overpriced PC Power and cooling units for SLI/Crossfire. As long as you get a quality 600W+ PSU, you'll be fine. I even ran 7800GTX SLI with a OCZ Modstream 520W and never had issues, although I don't recommend that PSU for use like that. In fact I now run a 400W PSU for my system and one of those PCI-E PSU's for my video card. It's not about the wattage, it's about the amperage.

Reply With Quote
  #3 (permalink)  
Old February 12, 2007, 03:42 PM
Babrbarossa's Avatar
Hall Of Fame
Join Date: Dec 2006
Location: New Brunswick
Posts: 3,735

My System Specs


AMD's probably just hoping that they can get everyone to rush out and buy the 1KW psu's that they'll need to have if they want to run r600's
Reply With Quote
  #4 (permalink)  
Old February 12, 2007, 04:09 PM
sswilson's Avatar
Join Date: Dec 2006
Location: Moncton NB
Posts: 17,850

My System Specs


Heh... no kidding.

I'm not so sure it's such a stretch to say that folks are going to need 700/850+ PS's as the norm in the near future.

I wish I had the coin to pick up a high end 1 or two rail PS. I don't have a lot of faith in the quality of the great majority of multi-rail ones, especially if folks are running dual vid cards.

When you look at the way most multi-rails are set up, the first Pcie conection is usually dedicated to the graphics card, but Pcie2 is often shared with other hardware.

Add to that, the facts that most mobo's now require the use of at least one auxilliary plug, many enthusiasts are turning to WC or extra fans as well as pushing stock voltages up (plus more mem sticks), & we're all using a lot of powered peripherals tied to the USB ports.

I'm surprised that we manage to get any system powered up properly without a true single rail PSU that is designed to spread the load evenly.
ASUS ROG Strix Z370-G Gaming (WiFi AC) / i7 8700K / 2X 8G XPG Spectrix D40 (3000) / XFX XTR 750 / ASUS Strix GTX 1070ti
AZZA Titan 240 / Custom WC / Intel 730 Series 480GB SSD / Intel 760p 512GB NVMe / Seagate Barracuda 1TB / ASUS SWIFT PG279Q
Dell Optiplex 3020 / Intel Core i3 i3-4160 / EVGA GT 1030 SC / 6GB DDR3 / Samsung 850 EVO 500GB SSD/ Samsung 27" 1080p (Curved)
Dell G3 - i5 8300H / HP EX920 512GB NVME / 2X8GB HyperX Impact / 1TB SSHD / GTX 1050ti / N156HHE-GA1 120HZ Monitor
Reply With Quote

Thread Tools
Display Modes

Similar Threads
Thread Thread Starter Forum Replies Last Post
e6600 Over clocking limit? mattydies Overclocking, Tweaking and Benchmarking 12 December 21, 2007 01:03 PM
Modular power supplies - what do I really need etc Nodscene Power Supplies 3 December 11, 2007 05:49 AM
Choice amongst 4 power supplies and a little help Eleazar Power Supplies 12 October 20, 2007 10:21 AM
High powered power supplies with loud fans Misoprostol Power Supplies 8 April 23, 2007 01:34 PM
Power Supplies enaberif Power Supplies 1 January 25, 2007 12:17 AM