BFG 7800 GTX OC SLi problem

NFL_Psycho · 12 Feb 2006 at 11:06

Current setup is:
AMD FX57 CPU
ASUS A8N-SLi Premium MB
2x250GB Western Digital SATAII HDs
2x(2x1GB) OCZ Platinum DDR
Sounb Blaster X-Fi Fatal1ty
BFG 7800 GTX OC GPU
OCZ 520W Modstream PSU
Windows Pro XP X64

Just bought 2nd BFG 7800 GTX OC GPU. Installed in, connected all power cables up and fitted the bridge. Turned PC on, MB BIOS checked fine, waited for windows to boot up...and it didn't. Then a screen stating windows failed to open properly appeared and gave options to open windows in safe mode/ previously settings that worked etc. Checked MB Bios Settings for SLi and it was on AUTO. So selected Dual Graphics (SLi) and same result...windows didn't open. Changed bios to single graphics crad and windows worked fine. I don't know why windows won't boot up when MB bios set for Dual graphics cards. Help Please before head goes bang!!!

chaparral · 12 Feb 2006 at 12:30

Boot up with a single card and unstall all the nvidia display and motherboard drivers then trying booting up with the daul cards fitted.

Use drive cleaner pro to make sure all the drivers are deleted from your system..

NFL_Psycho · 12 Feb 2006 at 12:50

Would drivers cause the problems I'm experiencing? Surely removing all drivers, booting up with sli n avin to download drivers (same ones) again would not change anything.

marc2003 · 12 Feb 2006 at 12:52

NFL_Psycho said:
Would drivers cause the problems I'm experiencing? Surely removing all drivers, booting up with sli n avin to download drivers (same ones) again would not change anything.

you'd be surprised....

chaparral · 12 Feb 2006 at 12:54

NFL_Psycho said:
Would drivers cause the problems I'm experiencing? Surely removing all drivers, booting up with sli n avin to download drivers (same ones) again would not change anything.

Went windows fail to load right after installing new hardware.It's normally means a driver error is causing the problem..

You should always unstall your drivers first for the hardware your upgrading.

Went installing new drivers for your bfg cards use the 81.98 nvidia drivers there about the most stable ones.
And make sure you install the SLI nforce motherboard drivers.

NFL_Psycho · 12 Feb 2006 at 13:02

Done some research and found that:
BGF 7800GTX draws about 16Amp off the 12V and about 190W.
The OCZ 520W Modstream only supplies 28Amp on the 12V so trying to run 2x BFG 7800GTX in SLi would need 32Amp of the 12V rail and 380W, which the Modstream can't provide.
Could this be why Windows will boot when setting Bios to just run a single GPU even when both GPUs are installed? ie the 2nd GPU is not drwing any power to run as it isn't enabled in bios. But when I enable dual cards in bios the extra power needed to actually run the 2nd GPU jus isn't there so the system can't even get to the Windows boot up.
Bios can detect the 2nd GPU as when set to Auto on SLi option it tries to run both GPUs. Also when Ive got into windows with only single GPU mode in Bios, the AI Selector of ASUS detect the 2nd GPU as I get the option to switch to SLi (fails when selected though as it has to reboot to do this). So to me the drivers are ok its just the lack of amp rating on the 12V rail that won't let the system get to boot windows as there isn't enough power.

chaparral · 12 Feb 2006 at 13:06

There's no problem with your power supply..Am running two overclocked 7800gtx 485/1300 on a 350watt power supply with no problems..

Your OCZ 520W is a very powerful psu which can easly coupe with daul 7800gtx 256mb cards in sli.

Plus...Your 7800gtx's are not on full load went windows is loading..

matt100 · 12 Feb 2006 at 13:09

why not just do whats been suggested?

I'd even try bashing F8 as soon as the machine has POSTed and start up in safe mode.. you'd be very very suprised what hardware can do to windows bootup.

An OCZ 520w will be fine for this setups I'm sure.. either way when there isn't enough juice you should still get into windows and then get an error message saying you haven't got enough power. It shouldn't stop you booting altogether.

NFL_Psycho · 12 Feb 2006 at 13:10

I'll give the drivers ago. The fun of uninstalling drivers awaits

chaparral · 12 Feb 2006 at 13:13

NFL_Psycho said:
I'll give the drivers ago. The fun of uninstalling drivers awaits

Just be glad it not ati drivers..Ati drivers take far longer.

NFL_Psycho · 12 Feb 2006 at 14:03

Retried 81.98 nvidia drivers and same result. I'm guessing I'll need to redo nForce 4 SLi drivers, but I need X64 compatible ones. nForce4 AMD Edition - Windows XP Professional x64 Edition is the driver I've found but it doesn't say SLi. Is this the right one even though it doesn't state SLi?

chaparral · 12 Feb 2006 at 14:12

NFL_Psycho said:
Retried 81.98 nvidia drivers and same result. I'm guessing I'll need to redo nForce 4 SLi drivers, but I need X64 compatible ones. nForce4 AMD Edition - Windows XP Professional x64 Edition is the driver I've found but it doesn't say SLi. Is this the right one even though it doesn't state SLi?

Try these

nForce4 AMD/Intel X16 - Windows XP Professional x64 Edition
Version: 6.83
Release Date: February 2, 2006
WHQL Certified

http://www.nvidia.com/object/nforce_nf4_winxp64_x16_6.83

NFL_Psycho · 12 Feb 2006 at 14:13

Cheers for that just found it too. I'll give it ago.

NFL_Psycho · 12 Feb 2006 at 14:33

tried reinstalling graphics drivers and nForce 4 x16 x64 drivers and then installing 2nd gpu and same result as before. Am I missing something out of the installtion process either with x64 drivers or on the A8N-SLi Premium MB?

Nuclearbaggins · 12 Feb 2006 at 14:45

Have you got a 4 pin power plugged into the motherboard just above where the top card is its for the ez sli thing, i had no joy when that wasnt powered up sorting my 7800's.

matt100 · 12 Feb 2006 at 14:45

NFL_Psycho said:
tried reinstalling graphics drivers and nForce 4 x16 x64 drivers and then installing 2nd gpu and same result as before. Am I missing something out of the installtion process either with x64 drivers or on the A8N-SLi Premium MB?

have you got the extra molex plug in the board by the top gfx card?

NFL_Psycho · 12 Feb 2006 at 14:47

Yeah I fitted the EZ Plug and the red warning light stays off so thats fitted ok.

chaparral · 12 Feb 2006 at 15:09

Pull out your soundcard and try booting up..And anything else that can be disconnected in your system..If it works then you need to reconnect or put back one thing at a time to workout what it is..

And if you do find out what it is..Please let us know before disappearing off to play games & benchmarking for the next week.

Am off to work now..I sure i be back on here some time later..

By the way..welcome to the world of PC hell.. I come to understand PC systems do not like human beings

They do everything possible to really stress you out and ***s you off..(And they normally win very good at it at well)

NFL_Psycho · 12 Feb 2006 at 15:17

i'll rip it to bits n try it. It all works fine until I stick the 2nd GPU in. They may be a pain in the butt but we couldn't live without em!

NFL_Psycho · 12 Feb 2006 at 16:06

I got it workingg woooooo!!!! took everything out. Shoved both gpus in n it worked, added sound card..still worked, then added fan controller, fans n uvs n dvd drives...still worked, then added 2nd stick of ddr (2gb total)..still worked, added 3rd stick ddr...worked but showed only2.75gb ram. added 4th stick ddr...didn't work. So I can have my system running with 1xGPU and 4Gb ddr OR SLi 7800GTX and 2.75GB ddr!?