Asus P5K-E with Nvidia 8600 GTS failure to boot

I am a little uncertain as to where this question belongs as the problem could be one of several things. I hope you will bear with me.

I recently upgraded my system in two steps. The original system was:

Zalman M460-MPS (460 W)
Asus A8N-sli premium
AMD64 3200+
1GB kingston ram (forget the specifics)
Point of view nvidia 6800 GS

I bought myself a new Point of view Nvidia 8600 GTS which works absolutely fine in the old system.

Then I upgraded most of the rest:

Asus P5K-E/wifi
E6750 core 2 duo
Corsair Twin2X2048-6400C4DHX (2GB)
I haven't touched the bios so it's still 703 (or something like that)
The hard disks, psu,etc are all the same.

If I install the new graphics card in the new system the computer will not even reach the bios. The fans spin for a second, stop, then try again. I have made a few observations:

1) The new system works fine with the old graphics card therefore there is no problem with the ram, etc.
2) If I try the new card (thus causing the failure) then replace it with the old one I get the same symptoms and no boot.
3) If I reset the CMOS the computer will then boot fine.
4) On a few occasions I could get it to boot with the new graphics card - I even installed the new drivers - but after unplugging the computer in order to move it I had the same problem again.

Since the computer doesn't even boot and resets very quickly I presume I don't have enough juice in the psu. If that's the case does anyone know why I need to reset the cmos when I replace the old card? In addition, why would the new graphics card work fine in the old system if it's so hungry? Does the new motherboard/processor consume a lot of extra power compared to the AMD? Or perhaps I was right on the edge with the old system and the new bits pushed it over the edge.

I note that the P5K series has been associated with some boot issues although I presume this isn't the case for me since it boots fine without the 8600gts.

Any help would be appreciated since I would like to understand the problem before buying a new psu or shipping back some components.

That's what I thought but I'm confused by the need to reset the cmos to get the old graphics card working. I spoke to a guy in a computer shop and he felt the psu should be ok (but then I was trying to describe the problem in french so translation may have been an issue).

It turns out the problem is nothing to do with an underpowered psu. I bought a corsair hx 620 and I still have the same problem.

I've updated the bios to the latest (non-beta) version and still no luck. I guess the question is whether:

a) there is a problem with the graphics card (despite it working fine with the old motherboard)

b) there is a problem with the motherboard (despite it working fine with the old graphics card)

c) the two just don't like each other. Does this happen?

Which would you send back (or should I send both)?

I had the exact same problem!

It'd work if i reset the CMOS but if i were to move it back to where it was originally it'll happen again. I have a POV 8600GT graphics card and ASUS motherboard.

The power supply i have is pretty crap so im gonna try a higher powered one and see if that works.

The motherboard i have is the ASUS P5K-VM AiLifestyle as well as OCZ 2GB Platinum RAM. This didnt actually happen when i first built the computer it was a few days after that it started happening.

When it first happened i put it on a work bench and took the CMOS battery out, put it back in and it worked. Then when i moved it back to where it normally goes it stopped booting again. If im really careful at placing it back it works but now its got even worse and it doesnt boot at all, even after resetting the BIOS.

i have a simmilar rig,
asus p5k-e/wifi
cd2 e6300
8600gt
4gb ocz ram
650 psu
nzxt hush
160wd hdd
i havnt had problems with boot up, apart from s.m.a.r.t saying hdd is bad and should back it up and replace. tried a maxtor 160gb hdd and again it said hdd is bad. IS THIS A MOBO/BIOS PROBLEM?

Same problem, when i turn on pc nothing happens besides all fans are turning.
Nothing comus up on the screen not even bios.

P5K-E mobo, have had it for over a year the same setup and besides adding 2more gig ram a few months ago i didnt change it, i never overclocked anything. I do have had same booting probs in the past that appeared &disapeared spontaniously.
Since then i usualy dont turn it off a lot (standbymode)
But yesterday i did (stupid me).. and this morning i got a half day off (was gone test the new gta on pc) instead i have had 4 hours of trying to boot... i removed the battery for about 3 minutes, but it didnt do any good.

specs:
P5K-E wifi edition
Dual core E6750
4gig ocz Reaper 1066 Ram
EN8800 GTS 3d card

Now my question, is there anyone that had this and actualy found a solution? (besides buying another mobo or hoping it starts again?)