Help, no video with new system

[bigjoe1975]

I'll try to keep this short.
Had 1 Intel D915pbl mobo that was doa with no power whatsoever. Got replacment and now I have power, but no video. My cpu, psu, hdd, and optical drives are carryover from my previous system. New components are: mobo, memory Crucial ballistix pc4200 2-512, and XFX 7800GT PCI-e. I was able to test the memory in another system and it is ok. unable to test video card though.
I did get video the first 3 or 4 times I powered up, but the system would lock while post-ing. Every attempt after I got nothing, just fan noise. I reseated video, memory, and cpu, still nothing.
I'm thinking I got another bad mobo. Although, the cpu could be bad as well.

All opinions are welcomed. Thanks.

 

[montag451]

any beeps when you disconnect the vid card?

 

[bigjoe1975]

No beeps when remove video or w/o memory.

 

[montag451]

Thats not very good -
Are you sure the mobo sound is plugged in?
If yes, I would suspect a dodgy mobo or cpu. -

Just to check though.....
Disconnect everything from the psu, and from the mobo.
Now,
Plug in the following only to the mobo:
psu
4 pin cpu from psu
mobo sound
cpu+fan

What happens now when you touch the button switch together with a screwdriver? (You did remember to unplug everything, didn't you?)

 

[bigjoe1975]

Montag,
I figured it out. Looks its the mobo. It won't boot in dual channel. With either stick of memory installed separately it boots fine. With both in dual channel, no go. If I put both in, but not dual channel it boots fine.
Any thoughts on what would cause this?

Sorry for the slow response.
Thanks

 

[montag451]

Do you have to enable dual channel in BIOS?