I recently built a new comp aprox 6 wks ago. It has been working flawlessly, no problems whatsoever. Specs:

E6850, 8800GT X2 in SLI, 2g OCZ DDR2 800, ASUS P5N32-E SLI mobo, Sound Blaster X-Fi, 2 SATA 150g raptors, 1 IDE ATA/133 HDD.

This week I installed a H2O cooling setup with a CPU block and 2 GPU blocks provided by Koolance. Everything installed fine, absolutely no leaks.

My problem is that once I finished installing the cooling setup my computer refuses to boot. When I turn it on everything turns on (fans, cooling setup, HDD's etc.) but there is nothing on the monitor screen. It won't even boot to BIOS, the yellow light on the monitor power button stays as is. I hear the initial beep from the MB like it is turning on but then nothing. My main HDD spins occasionally aprox every 30s (for only about 2s at a time) but doesn't stay on like it would when it normally boots. I have checked ALL connections, wires, PCI slots; everything is intact. I have unplugged all HDD's except the main, still no change. I have removed excess fans/cooling/lights/etc. from PSU, still no change.

What I am thinking to do next is remove one of the GPU's and the sound blaster, leaving only the main GPU in. Other than that I don't know what to try, I am at work now so I will try everything tommorrow morning. Any help/suggestions would be greately appreciated. What could be the problem? PLEASE HELP!

This is just a guess here, but maybe the new cooling setup put too much of a strain on your PSU. What are the specs on your PSU ?

I thought the same thing, I actually unplugged the cooling apparatus for a quick boot and nothing changed.

I was checking online too and saw that some mobo's won't boot if there is no cpu fan connected to MB, is this true? If so, could this be my problem? Obviously it is H2O cooled so there isn't a cpu fan but there is a regular case fan that I can try and connect to the cpu fan spot on MB. I will try that tommorrow. Keep the suggestions coming.

"I was checking online too and saw that some mobo's won't boot if there is no cpu fan connected to MB, is this true? If so, could this be my problem?"

That is a possibility.

Trying a three wire fan connected to the cpu fan header sounds like a good idea, but I think something else is wrong. Usually if your mboard has that safety feature, it boots normally and then shuts itself off in a very short time if no rpm is detected from the cpu fan - it wouldn't kill your video.

Did you unplug the PS or otherwise remove the AC power to it when you were fiddling around inside the case? ATX mboards are always powered in some places as long as live AC is being supplied to the PS, even when the computer is not running. If you didn't remove the AC power you may have damaged something merely by plugging in or unplugging a connection or component. This is especially crucial for an AGP video card - both the card and the AGP slot have two rows of contacts vertically that are staggered in relation to one another and you can easily damage the card and/or the slot.

Did you get ANY water on the mboard?

See response 2 in this - try cleaning the contacts on the ram modules, and making sure the modules are properly seated:
http://www.computing.net/hardware/w...

Do the same thing with the video card, and other cards.

A faulty or damaged PS can produce strange symptoms. They can partially start up, yet the mboard will not fully boot and you commonly get no video.
Try another PS.

So I finally figured out what the problem was, you guys will like this one.

So I started by taking out the sound card, no change. I then took out the second GPU and the comp finally booted. So now I know that it was either a PSU problem or the GPU itself. I took out the good graphics card out of the first PCI-E slot and inserted the "bad" one, no boot this time. So that rulled out the PSU as being the problem. I then took off the H2O heatsink from the "bad" graphics card and analyzed it, everything looked ok except for one memory module wasn't covered by a thermal pad. I placed the pad on, put the heatsink back together and plugged her in. Still nothing!!!

My last resort was to replace the screws that came with the heatsink with the screws that came with the 8800gt gpu. . . . Everything is now back to normal. My H2O cooling set-up works without any flaws and the system is running as quick as can be. Who would have thought that these screws were the cause of all my issues. It must have been a grounding issue b/c the nvidia screws came with metal 'spring' washers and the heatsink just came with a plastic washer. The funny thing is that the other 8800gt is running fine with the heatsink screws, I don't want to touch it.

Now time to OC!!!