I have a Quad core Q9930 CPU, 4GB (2 sticks) of DDR3, 250GB 3.5'' SATA Hard disk and a Powercolor HD3870 graphics card (512mb) inside a TA-8 series Asus chassis case. Using a 650w TX Series ATX PSU to power it all along. Motherboard is an Asus P5QC. Connected to this is a 24" Dell monitor and so I powered it up, waiting for the magic to happen. Disaster! The computer isn't sending a signal to the monitor and there are no "POST" BIOS beeps. Opened it up and all the fans (chassis, graphics and PSU) are spinning away as they should and there's a green LED on the motherboard but there's nothing getting to the monitor. So then I wondered whether there was a problem with the PC speaker as there weren't even any beeps to notify hardware failure or anything else so I checked that was connected in properly but also decided to remove the RAM and power up again. This time it beeped once and then twice more quickly. According to Mobo manual, this means no memory detected. Ok, fine. At least I know the PC speaker's working. Also when I power it on, the CD drive's working fine but the HDD light on the front of the case only flashes once when coming on but then stays off. It can be left for a while and doesn't power itself off like I've seen in other similar problems to this and there are no obvious hardware failures. Doesn't respond to anything pressed on the keyboard. Anyone know what the problem is here? Any glaring or obvious mistakes? Hope I've included everything.

The fact you get a bios beep error when no RAM is installed indicates that at least the CPU is functioning and the motherboard is probably OK. If the powersupply is a Corsair unit as described here: http://www.corsairmemory.com/produc... then It looks to be ample and would be a trusted brand. That leaves the graphics card. Did you connect the appropriate powerconnector? If you leave out the graphics card and attempt to boot do you get any error beeps? Disconnect any/all drives. Remove any extra PCI devices and ensure nothing is plugged into USB. Leave only one stick of RAM and the keyboard. No mouse. Can you get any display? Is the drive you have also new and unpartitioned? If so then it isn't surprising that you saw only a brief LED activity. Since there is no operating system or bootfiles on it the BIOS would look and then bypass it to display an "Insert Bootdisk" or other error message ( If your display was working) All this leads me to believe your graphics card is the problem. I once had one DOA out of the box. The only way to know for sure is by testing a known good card in your system or test your card in a known good system. Goin' Fishin' (Some day)

Update: Tried booting with disconnected DVD drive and HDD and it gave me a black screen with a flashing cursor in the top left corner. Also beeped once and then again but held the tone forever.

Thanks for the reply. I hope you're right because I'm less-bothered about that card and was considering a better one anyway. I'll have to get it tested on someone else's PC.

Did you benchtest the board before putting it in the case? If not, then that's a very important step. I suspect that maybe the motherboard is touching a metal part of the case. You said that when you took the ram out, it beeped the "no ram" beep code. After that, did you try each of the 2 RAM sticks individually? WinSimple Software

Mild breakthrough with this. Somehow a drive to new house may have knocked a loose connection in to place or something but it's now picking up the VGA and beeping once when powered up. However, ...(!) it's now not picking up a PS2 keyboard at all and this has been tested ok on another machine. Monitor now displays "Express Gate is not installed on your system or the installation is incomplete. To get Internet access within seconds of starting your computer, please use Express Gate Installer to install Express Gate. Press any key to continue (CE306080CE64)" And therein lies the problem with no keyboard. Any new suggestions?

CONCLUSION: Turns out the RAM (OCZ DDR3) doesn't seem to "like" the Motherboard or vice versa. Worked fine with DDR2 in there. Resolved if I can pick up some decent RAM now!