Can my video card effect CPU core voltage?

[Fuelrod]

Question: Is it possible my CPU's core voltage could have dropped after adding a power hungry video card?

Background: I recently bought a Nvidia 260 GTX and after installing it immediately started experiencing crashes (i.e. random system reboots) while playing games. I've tracked it down to the CPU, and if I lower the overclock I don't have any problems. Nothing has changed except the video card and my system was rock solid stable before it was installed. Looking at the core voltage in CPU-z it seems to be lower than I remember it with my previous card. Could adding the 260 GTX cause voltage to the CPU core to decrease? How accurate it that core voltage anyway? The difference between my motherboard bios setting voltage and CPU-Z is 0.04 volts idle and 0.07 under load. When I'm looking at max voltage to the CPU, should I go by motherboard or CPU-z? Any comments are appreciated.

System: Gigabyte P35-DSR3 motherboard, Intel E8400 @ 3.8 GHz, 4GB Corsair memory, EVGA 260 GTX Superclocked, Corsair 520HX power supply.

 

[cusideabelincoln]

Instead of lowering the overclock on your processor, did you try to up the Vcore a hair and take note of the readings? I'm sure it's possible the GTX 260 is drawing more power from your Corsair and causing it to drop it's output the rest of the system. What video card did you have before?

 

[Fuelrod]

Originally posted by: cusideabelincoln
Instead of lowering the overclock on your processor, did you try to up the Vcore a hair and take note of the readings? I'm sure it's possible the GTX 260 is drawing more power from your Corsair and causing it to drop it's output the rest of the system. What video card did you have before?

Before I had a 8800GTS 640. I can up the core voltage and it becomes stable again. But that brings me back to one of my original questions, when I'm increasing the voltage should I go by the motherboard or CPU-z. I don't really want to go over 1.45V on the core and right now I'm at 1.425v in the bios but CPU-z reads 1.38v idle and 1.35v under load

 

[cusideabelincoln]

You can also monitor your PSU rails and various system voltages with a program like Speedfan. Gigabyte should also have utilities to monitor system settings. I would go by what these programs are telling you rather than the BIOS setting, since you may, like I said before, be getting voltage drops with the GTX 260 since it does use more power than the 8800GTS 640MB even though your PSU should be able to handle the load. This may be a long shot, but have (or can) you tried switching some cables on your modular unit?