TX750 makes Ethernet Port Noise on Standby -SB 5V Ripple ??

I am using TX 750 Since September 2011. It was seems good . 1 moths ago I changed mainboard from Asus p5b deluxe to MSI 975xPlatinium Powerup edition.Because Asus MB was dead

TX750 worked OK. But when I shut down PC , during SB mode Ethernet port makes high pich audible noise with MSI MB .

I remove MB and changed it another one but problem still continue .

Then, I borowed another PSU 550 Watts HEC Cougar brand from my friend .

No any Ethernet port noise aon Standby position with HEC PSU. But TX 750 makes noise on the Ethernet Port ( Iam sure , audible noise coming from Eth. port , not from PSU ).

I have oscilosscope , I removed TX 750 PSU completely from Motherboard and measured 5V SB Voltage ripple on the Purple cable of ATX connectors.

Yes I found a 6.66 kHz noise ( 0.15 msecond period) amplitude max 10 mV pp.and found 100 kHz HF noise at 10uSeconde period

But I checked another HEC brand PSU no any noise at low frequency .Only found 130 khz noise at 7 mV pp .

I suspicied that TX 750 PSU have a ripple fault .This ripple makes a ethernet port noise becuse during Standby mode ethernet port stay live and feed 5V stand by voltage

Do you know ? TX 750 have a low frequency ripple as attached picture ?. Is this a normal behaviour of Corsair TX 750 or not.

Because My motherboard is new and I donT wznt to use it strange ripple TX

750 PSU.

How about opinion about attached 5V standby ripple noise/

Is this a normal behaviour of TX 750 or has a ripple problem or not /

Thanks for interest/

PSUTECH