7900GT strange behavior

[imported_tsonjjd]

Ok bear with me a moment. I just upgraded my pc. I bought these new parts:
ASUS PN5-E SLI
E6750 Core2Duo
2 GB OCZ Platinum Rev 2 DDR2-800
Vista Ultimate
WD2500KS 250GB 16mb cache SATA drive

I reused my:
480W Antec Neopower
Lian Li PC-7 B plus
Sony NEC Optiarc CRX320EE-BS DVD 16x
EVGA 7900 GT

I am planning on replacing the 7900GT with a 8800GT once it arrives. Anyway I built the PC using the 7900GT. The PC booted fine and I was able to install Vista fine. I installed drivers/software and everything appears to be working. I did a mild OC to 3200mhz on the CPU going 1600 on the FSB and leaving the memory alone. I am able to play games such as COD4 on it. What's strange is that I happened to look in the case and noticed I had forgotten to plug up the external 6 pin power cable to the 7900GT!! When I tried to plug the power cable (after shutting down of course), I restarted the PC and it looked like it was working but when I tried to log into Vista the screen went fuzzy and static like. I shutdown the PC using the power button then removed the external power cable. Everything works fine again. Why don't I need that power cable anymore? I did set the graphics slot to pci-e in the Bios. Anyone have a clue?

 

[nullpointerus]

Clearly, your 7900 GT has evolved beyond the need for a secondary power source.






Seriously...are you sure you were playing at stock clocks before?

Perhaps your 7900 GT, like so many others, developed (or came with) a problem with the stock clocks and it went unnoticed because of the auxiliary power connector being disconnected. But, in this case, shouldn't there have been a warning from the drivers?

 

[imported_tsonjjd]

My previous PC that I reused from was a AMD 64 3800 on a MSI K8N Neo4 SLI platinum board running XP Pro. The 7900GT was running on it fine and I had the 6 pin power plugged up.
The card is fairly new as I had to RMA my first EVGA 7900GT when it started artifacting. That PC was completely stock clocks.

I am not OCing the 7900GT either in this new PC. This issue isn't a big deal as I will replace it with an 8800GT next week, but it is just strange that I am able to run it without that power plug (I'm on the pc right now).
My monitor is a 22" Samsung and I'm running at 1680x1050.

 

[nullpointerus]

Hmm...that IS odd.

What I meant is that the card might have been running at lower-than-stock clocks when the auxiliary power cable was disconnected. That was my first guess, but technically the drivers are supposed to warn you when the card is running in low-power mode.

Maybe something happened to your card (static?) during the transition.

Or perhaps your PSU is just near its maximum (in which case your 8800GT will have problems, too).