Q: System:
Gigabyte GI 81EXP
P4 2.0a
Nvidia 6600 GT
I just upgraded one of my machines from a Ti 4200 to a 6600 GT. Prior to upgrading the CPU is OCd years (usually running on 2.5 or 2.6). However, after replacing the video card the system will not boot at all if only a bit OCD (tried as low as 2.1) 0.
I tried enabling the AGP / PCI lock, upping the AGP voltage, etc.
Any suggestions for how I could order this?
UPDATED 11-21-2005: food has been replaced as proposed and issue persists.
Re:If the card is performing Ok, and the system is stable at STOCK, then it seems strange if it was still the cards problem. When abouts does it not allow an overclock – 25Mhz OC, 50Mhz OC, 75Mhz OC? Or nothing? Maybe some other value has been changed in the BIOS for some strange reason?
Possibly you could try updating the BIOS?
Re:could it be a bad card. i swapped an evga 59000se to a leadtek 6600gt no problem. intel p4 2.4c running at 2.8
Re:Does your motherboard lock the AGP bus speed? Perhaps it doesn't and the 6600GT can't handle the increased speed? Somewhat unlikely, but I can't think of anything else.
Re:Unfortunetly I cant put the old video card back in; I already sold it off…
Temps are ok?
Temps appear to be just fine (just checked CPU & GPU). Besides if it was a temperature problem I would expect it to post sometimes (while cool) but not others (when hot); especially since I've tried overclocking such a small amount (100mhz is 5%)
Did the bios get reset or anything during the process?
I've reset it (default optimized, default failsafe) several times while troubleshooting in hopes that I had screwed up a setting or something but doesnt seem to make a differance.
This is such a strange problem; I'm stumped here also. I keep bumping this thread in hopes that the right person will come across it.
Re:Just to make sure, try putting the old card back in and see if you can get the overclock back. It probably will, but its pretty easy to swap video cards so I'd try it just to make sure it was the video cards fault. You could compare what kind of cpu voltage the bios is reporting with the old card versus the new to give you some idea whats going on.
This is kind of a tough one though. My guess would have been the PSU as well, but honestly I thought even your old one would have been up to the task.
Temps are ok? You didn't knock the HSF or anything? I'm kind of stumped. Did the bios get reset or anything during the process?
Re:Replaced the PSU with a new Antec 500w unit and the system is still having the same problems.
Re:even if you did use a second exterior psu to power the card you would still have the same problem. Ive been through this headache before when I had an enermax 350, it didn't have the amps needed to overclock and supply juice to mobo for the gpu, I bought a new psu and problem solved.
Re:I had your same problem with overclocking.
I would suggest it's your PSU for sure, but one way to make sure is to check your voltage on the 12v rail and make sure its not less than 11v
Re:I didnt think it would be the PSU; but used this as an excuse to replace it anyways as there were a couple who suggested it…
Re:why would it be the pus when even a minor overclock won't work?
Re:Replaced the PSU with a new Antec 500w unit and the system is still having the same problems.
try disabling agp fastwrites
Would that effect the system's ability to POST?
Any other suggestions?
-Erik
Re:i don't know if this might work, but try disabling agp fastwrites
Re:Probably is the PSU – the AGP 6600GT has a bridge chip which is quite power hungry, so your probably not getting enough power to all the components.
[EDIT] Which is stupid of me to say if I had read your last post….
[EDIT 2] Although still, though, it'll be eatging 45watts from the AGP slot through the first PSU, which the ti4200 wouldn't have come close to. So probably is PSU afterall. Unless you try something like a 400watt branded PSU, just using anotehr PSU for the molex connection doesn't mean it's not the PSU, as it could still not be getting enough power.
Re:I was close, it is an enermax but it is only 300W. Not a lot but should still be enough to power the system.
To help rule out a PSU issue I took another power supply and ran one of its 12volt molex connectors into the 6600gt however the problem persists. Even a minor overclock and the system will not post.
Re:could you tell more about the PSU i.e. brand, total power or 12V amps
I'll have to verify when I get home tonight; offhand I think it's an enermax 350W. I had considered a power issue also, but seems unlikely considering it seems to have the issue when only overclocked slightly.
FYI – the video card is a PNY VCG6600GAPB 6600GT 128M, and yes I do have the 12v plug attached 
Re:I'm using the latest bios revision (though it's 3 years old). Shouldnt be a driver issue; when the CPU is OCd the system wont even post (that motherboard has the "dual-bios" so when it cant post it defaults to fail-safe and restarts).
Seriously annoying issue…
Re:i think it's your PSU, but i might be wrong. could you tell more about the PSU i.e. brand, total power or 12V amps
Re:??? ive never heard of this…you using the new drivers, new mobo bios, psu cant handle it…? im kinda out on this one.
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