Leadtek WinFast PX9600 GT Extreme (S-FANPIPE), randomly hangs at boot

Hi guys,

I'll begin my post by firstly specifying that I'm quite desperate and this is the reason I have registered here (as a last resort) hoping to find someone that can really help. I see a lot of professionals here and I do hope I'll find at least some hints here

It is almost 4 days since I've started installing and reinstalling and reinstalling OSs, drivers trying to figure out what's happening.

This is the scenario:
I've bought some new hardware components to build a PC for a friend of mine. A medium-price gaming PC.. Everything went out perfectly until I've firstly noticed a Windows XP Pro 64bit freeze during boot (it hanged at that loading screen, the moving bar just stopped). At first I thought it is some coincidence or who knows.. but the problem persisted. Started removing drivers and noticed that my Leadtek drivers were causing this. What is curious is that the system wouldn't hang constantly.. Many times it would just freeze there for about 1-2 seconds and the bar would continue to move and boot normally.. But in majority of cases, it would hang at that point. After removing my 9600gt drivers the boot was perfectly, the bar wouldn't even hang for half a second.
First, I thought "gosh, this is a driver issue" and downloaded the last XP 64bit driver from nvidia, installed, but again the same symptoms, same hangs.. Then started to search the internet, found no relevant solutions so far, just mysterious cases leading maybe to some driver incompatibilities, or maybe to hardware issues or something, but nothing clear enough..
My next idea was of course to try different driver releases, tried the nvidia archive and betas, but without any success.. Reinstalled the OS, without installing any motherboard drivers. First thing to do, installed the latest nvidia stable, but the same problems. With nvidia drivers on, the system would hang in 60-70% of the cases; without the drivers, no problem... Also tried of course windows update, got it up to date, reinstalled different driver versions, no success either..
Next try was to switch to Vista 64bit thinking that maybe XP 64bit support isn't too great.. Well, it was in vain, the same problems (in Vista, it would freeze after that moving bar, leaving me with a black screen). Well, my last idea was to try some 32bit OS, and tried again Vista.. THE SAME: the system would nicely boot ALL the time without the graphics driver, and would hang with the driver installed...


I really don't know what to do, because I can't yet figure it out what is causing this. I also should mention that on successful system boot the system works PERFECTLY. No problems, no hangs, played CRYSIS for hours continuously, run 3dmark 2006 several times, and everything works like a charm...
So, please.. if anyone had this problem, or anyone can help, any suggestion is welcome. I'll post below my precise system configuration and some interesting Vista bootlogs that should reveal the place where the system randomly hangs..

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SYSTEM CONFIGURATION:
MB: MSI P45 Neo3 > http://global.msi.com.tw/index.php?func=pr...o=1&cat2_no=170
CPU: Intel Core2 Duo E8400 3.00GHz Wolfdale Box
RAM: A-DATA 4GB DDR2 800MHz CL5 Gaming Series Dual Channel Kit > http://oc.adata.com.tw/product-series.asp?sid=02
VIDEO: Leadtek WinFast PX9600 GT Extreme (S-FANPIPE) > http://leadtek.com/eng/3d_graphic/overview...1&pronameid=418
HDD: Western Digital 640GB SATA-II 7200 rpm 16MB Caviar > http://www.wdc.com/en/products/products.asp?driveid=394
CASE: Regular..
PSU: Nothing special, but with two 12V rails (15A + 16A) which i use to power up the Leadtek using the power connector and included adapter -- anyway the voltages stand well when playing Crysis, my multimeter notices just a dropdown from 12.25 to 12.10 on one of the rail


BOOTLOG (Vista 32bit) > http://forums.nvidia.com/index.php [...] st&id=9270:
- First boot (8 20 2008 23:10:10.375) corresponds to a successful one;
- Second boot (8 20 2008 23:11:16.375) is the one that hangs;
- Third boot (8 20 2008 23:12:11.375) is one made in safe mode after the hang

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LATER UPDATE:

I have borrowed another Graphics card from a friend, this is basically it's twin brother:
Leadtek WinFast PX9600 GT (S-FANPIPE) > http://leadtek.com/eng/3d_graphic/overview...1&pronameid=419
Basically, it's the same card but the simple version, not Extreme (overclocked one). I've also tested the same system under the same conditions but with this card this time, and I have updated symptoms:

The system still randomly hangs, but the percentage of boot failures is much much lower !
To give some estimated percentages, the simple version would hang on 5-10% boot cases, and my Extreme version would hang on 60-70% boots.. And like I've said before, if I remove the drivers everything is fine with both cards. Both cards cause freezes at the same moment during boot.

Well, considering those news, I am also thinking about a communication problem (with the mobo, something related to frequencies ?), or PSU problem ? (although benchmarks, crysis work perfectly if it boots, and sticking another HDD in the rack doesn't worse things)

..any hand is really really appreciated. Thank you very much in advance