Motherboard/memory problem. Pls help!!

[t_y]

I just got my rma asus p5n-e sli last night and was trying to build my system:

Intel P4 630 (3.0Ghz)
2X512MB 667Mhz Corsair Value Select
OCZ Powerstrem 520W
Video card is an ATI that I got with my old Dell.
I also have a watercooling system with waterblocks on the CPU and Northbridge (I already had a fan cooler for the gpu). Let me know if more details are required.

When I first got it, I built the essentials outside the case and it started up okay, but I didn't let it run for more than 30 sec.

I built the system in the case with the watercooling system and I got a beep code. One long, two short. I resetted the video card and memory and the system worked, but not always. Sometimes it would start, but most of the time it wouldn't.
As of now, IF the system starts it will run for about 7 minutes before stalling in the bios with one stick of memory, but only 1.5 minutes with two sticks. I have tried using different combos of the 4 memory slots, but I get the same result. If it doesn't start, I get a continuous beep code (not beep, beep,....beep, but beeeeee...eeeeep). I have tried to clear the cmos, but that's no help.

I think its the motherboard or maybe a cooling issue. My watercooling system works (stock cooling cpu idle temp: 42oC, watercooled: 31oC) and I checked the northbridge block to ensure its in contact with the chip (And yes I'm cleaning off old thermal grease and using arctic silver). Right now, I have no clue what to do. PLEASE HELP! Thanks!

[LeftyAce]

Check the motherboard manual for what 1 long and 2 short beeps mean. Sounds like you may have a memory issue. Download and burn the UltimateBootCD (www.ultimatebootcd.com) and run memtest86+ off of it. You'll need to use nero or some other .iso burning utility; windows will not burn the file you download with the UBCD on it properly. If you don't have nero, deepBurner is a good free download.

[t_y]

Thanks for the reply.

I'm pretty sure the long beep-two short beeps means a video card problem. But I'm not getting that anymore. I had memtestx86 on a floppy disk. I was able to boot my computer with both memory sticks and ran memtest. It ran for 1 min before stalling...well I'm not sure if it stalled. The test stopped proceeding and the keyboard was not operable, but the little blinking asterisk on the memtest screen was still blinking. (?)

I pulled my cpu, ram (both sticks) and vid card and put them in my old Dell motherboard and it started without a hitch. I could not run the memtest (said that the disk was not a bootable disk), but I let the computer run in the bios for about 10 minutes and no stalling. I'm planning on replacing the motherboard tomorrow unless anyone else has any other ideas.