GeForce 620 card kills my SoundMax device

gang here's a new one on me. in 20 years of things PC I haven't seen exactly this, though I have heard of such.
I have 2 DC7900 desktops that are essentially identical [RAM is diff, but everything else same]. In the one, for HTPC duty, I have EVGA Geforce 630 GT low-profile. it was a breeze to install - everything works dandy. so I thought I would do it again. but this time, got a EVGA 620 GT. form factor etc the same but of course the IC's are diff. It "disappears" my builtin SoundMax [ADI] device. its gone. no appearance in bios IRQ settings, does not exist. Remove the card, and its back and just fine.

is this unresolvable? I see no way around it since there are no settings, as there is "no device"....:cry. DC7900 has two PCIe x video slots for dual cards. I've tried it in each slot, with same ugly result.

there's a secondary issue here I don't like also but don't want to overburden this post: unlike the 630 card, when the nvidia driver [same as on the other one] loads up, the card's onboard fan goes to 100% or so - and its a noisy bugger. if the nvidia driver does not load [I intervene] its nice and quiet like the other card.

any hope/suggestions? is there a way to monkey with IRQ's in hope the ADI device will suddenly resurrect?

 

Hello,

Is the computer connected with an HDMI or DVI interface to the monitor?

 

Have you tried disabling and re enabling the on board audio in the BIOS? Maybe disable the audio from within the BIOS, then install the Nvidia video card, get it configured how you want in Windows and then reboot, get into the BIOS and re enable the audio. I remember having to do something like that this years ago and I think that solved it for me.