Asus P6X58D Problems

Here is my setup:

Asus P6X58D
i7 920 (not overclocked)
EVGA GTX 260 core 216, 55 nm
Corsair DDR3 1600 (PC3 12800) TR3X6G1600C8 G
PC Power and Cooling 750w PSU
Swiftech MCP655 Pump
Swiftech Apogee XT waterblock
Swiftech 2x120mm radiator
2x Panaflo Ultra High Speed 120 mm fans

I just cannot get this damn thing to POST. I have swapped out PSU's (previously was a 700w Thermaltake) already and I've also tried another set of RAM (Super Talent, same speed). I've tried testing one stick at a time, but it just refuses to POST and the useless DRAM red LED stays lit. I've tried clearing the CMOS to no avail as well. I'm about to just throw this useless $300 paperweight on the floor in frustration. I need to get this system working relatively quickly and I really don't want to waste time RMAing anything that I'm not even sure is broken.

I have gotten the system to start up and run windows with all 3 sticks in with a 9600 GSO and a ATI 4850, however. I don't know why it just won't work with the GTX 260. I have tried both an EVGA GTX 260 and XFX GTX 260 (65 nm), both core 216 models.

I have tried just about everything I know short of getting a new board. It might be that the PSU can't handle the GTX 260, but this is highly unlikely since I've tried two different PSU's and the PC Power and Cooling 750w had previously been powering a folding rig containing an X4 955 at 3.8, 2x GTX 260, and 2x 9600 GSO. It should be easily capable of handling just one GTX 260 and the processor.

Any suggestions?

ok, so it works with a 9600 / 4850, and you can boot into windows
but when you stick a high end card in there, it dosent post at all?

does the power come on? and does anything come on the screen at all?

could the weight of the card cause the motherboard to shot out with the back of the case - try running it all outside the case

the psu is not the problem. i have a tx650 w on a high end i7 system

have you tried the gtx260 in a different slot? even though its not the correct slot, the motherboard should till boot

I have the same board and recently built a new gaming rig over the weekend with it.

I am sure you have checked something this simple, but I will mention it anyway. Did you plug in the power to your GTX 260? As antipesto mentioned, you should try the GTX260 in one of the other pci-express 2.0 slots and see what happens.

Is it possible to test the GTX260 in another system to help isolate the problem?

Yes, I have checked that the GTX 260 is getting power and I have tried different PCI-E slots.

You were right about the heavy dual slot card causing the board to come into contact with a particular standoff attached to the case (I had not screwed the board in there, just put a standoff underneath), which caused the board to short circuit. When I physically supported the card, there were no memory errors and the system booted normally. When I tilted the case upright (normally i tested the system horizontally), which takes the weight of the card off of the motherboard, the system booted normally. When I screwed in the motherboard at that standoff, the system would not boot no matter what card I used and it continued to give a DRAM error.

My question is, aren't these metal standoffs supposed to be used to support the motherboard? What good do they do if they just short circuit the board and render it unusable (something that I had not encountered with my EP45-UD3L for the E8400)? Are there any alternatives to these metal standoffs, such as plastic ones, or are there any washers that i can put to keep the board from coming in contact with them?

Edit: Unfortunately I am unable to diagnose the problem further because I was forced to leave my system at home when I returned to school today. I was hoping to get it up and running so that I could take it to school, but since it still needed some work I couldn't bring it to my residence at school.

At last check, I don't think I had more standoffs than necessary supporting the board. I am well aware of the fact that if standoffs are installed where the board does not have a screw hole, it can short the board. I am pretty sure that the standoff that is shorting the board is one that is technically "supposed" to be installed.