Computer does not POST

Hello everyone, yesterday my computer decided to stop POST-ing when i turned it on and the monitor showed a "no signal" message on the screen. I tried using 1 stick of ram and changing the sticks and reconnecting the power supply and hard drive and clearing the cmos but nothing seems to be working. On top of that, my case doesnt have a beeping mechanism to tell me what kind of problem im having so im just shooting blind here. Could anyone even try to fathom whats going on with my ridiculous problem? it all happened when i turned off my computer during a boot sequence while the computer was checking the contents of my external hard drive for some reason. Im completely fine with reformatting and reinstalling windows if only i could get a post on the screen and have things running again. heres my list of parts btw



AMD Phenom II X4 810 2.6GHz 4 x 512KB L2 Cache 4MB L3 Cache Socket AM3 95W Quad-Core Processor.

ASUS M4A79T Deluxe AM3 DDR3 AMD 790FX ATX AMD Motherboard.

CORSAIR DOMINATOR 6GB (3 x 2GB) 240-Pin DDR3 SDRAM DDR3 1600 (PC3 12800) Triple Channel Kit Desktop Memory

Antec Nine Hundred Black Steel ATX Mid Tower Computer Case.

CORSAIR CMPSU-650TX 650W ATX12V / EPS12V SLI Ready CrossFire Ready 80 PLUS Certified Active PFC Compatible with Core i7 Power Supply.

EVGA 896-P3-1265-AR GeForce GTX 260 Core 216 896MB 448-bit GDDR3 PCI Express 2.0 x16 HDCP Ready SLI Supported Video Card.

SAMSUNG Black 22X DVD+R 8X DVD+RW 16X DVD+R DL 22X DVD-R 6X DVD-RW 12X DVD-RAM 16X DVD-ROM 48X CD-R 32X CD-RW 48X CD-ROM 2MB Cache SATA 22X DVD±R DVD Burner with LightScribe

You need four things to post...cpu, memory, video and keyboard. If you're not posting you're missing one of these elements. The hard drive doesn't come into play until after you've posted.

today when i turned it on it posted, then it didnt display again but then i changed the input slot for the hdmi cable on the tv and then switched the source on my tv when it then displayed the log on screen for a second and went blank again.. im starting to think that maybe the gpu isnt able to display correctly because i had cleared the cmos and used the jumpers. how could i change the resolution during startup? or would i have to go into safe mode in order to do this?