Getting black screen when the machine boots up, switched out the motherboard for a new one, bought a new PSU, tried a different working graphics card, hooked the PC up to the TV so its not the monitor either. I've also taken out the battery to clear the cosmos, it just sits at the black screen, it still beeps on bootup and thats all it does, I also took out one ram stick, then the other, and put ram in different slots as well as booting up with no ram as well to see what it does.... I also took out the soundblaster card and unplugged my drives and dvd, just wont even let me get to the bios screen..... doesn't post or nothing.... My only conclusion is that the CPU is gone, but I have no way to test it, does anyone else have any thoughts what might be my problem? The new mobo has an onboard GPU, but i cant get into the bios to change it to my pci-express slot or disable that if indeed that is the problem, but still black screen even when i take out my main graphics card...

thanks for any replys!!

Is everything properly grounded? Also, when you disconnected everything and just ran the mobo/cpu, did you discharge the power completely before and then try starting up with just the mobo/cpu?

How many beeps are you getting? What's the length of the beeps? Can you record the beep error along with the board and CPU?

Just tossing this out there, but sometimes a motherboard will say it supports CPU XYZ. But sometimes, support for that CPU doesn't come until a later BIOS revision than some boards ship with.

Take note of the number/length of the beep and the check that against the error codes in your Motherboard manual.

It sounds like the only thing you haven't tested is the CPU. Since you've gone through some pretty exhaustive troubleshooting, my guess is that the CPU is dead.

Also - the motherboard doesn't have a built in GPU, those are built into CPUs.

Are you getting any kind of LED errors or beep codes from your PC speaker?

i seem to recall a bent cpu socket pin can cause this.

Thanks for the replies guys... As foe properly grounded yeah it is, as far as I can tell, I did have a loose screw in the case which I "thought" might be causing a short but its still doing the same thing when I found it and took it out.... No pins are bent on the CPU because when I switched out the mobo that was one of the first things I checked! I might also say that this CPU is old! its an AMD Phenom II x6 1090XT so it might just have failed, its 7 yrs old i believe should have perhaps mentioned that before!

The beeps! well their just the regular single start up beep, very quick... not an error beep.... beeped many times continously when i took all the ram out of course... but was fine when i put them back in.... @zelyre Yep I did think about that too, the newer motherboard I put in is a Gigabyte MA785GT-UD3H AM3 ready...if i need to get a bios update i don't know how to do that as I don't have any other cpu's to get back into windows...

Does your motherboard have some kind of USB BIOS flashing function?

Mine does, and the first time I booted the system after building it I got nothing but a black screen. I had pressed the BIOS flash button on the motherboard without realizing it, and the motherboard was waiting for the USB flash drive to be inserted. Once I toggled the button it booted right up.

Have you tried replacing the cable between the computer and the monitor?

@bane: That is something I haven't thought of yet... I'll take a look and see if it does.... @kidavenger Yeah I tried plugging it into my TV actually via the HDMI cable but same thing happens...

Tried the onboard graphics? Motherboard might be defaulting to that?

Ok it doesn't have a bios button reset on the actual motherboard itself... it does however have a Q-Flash, but it doesn't even seem to recognize the keyboard when I'm pushing del/end/F9/F12 to do bios or bootup options... Right now yes its connected to the onboard graphics coz that was my first initial thought myself..... I am not getting to the motherboard splash screen but that is as far as it goes, I get black screen and the machine restarts itself.... after a lot of restarts I did manage to get to the main bootup once, where I was able to see the RAM was recognized and okay.... but it went too fast to see anything else, all drives are disconnected at this point so it didn't see them.. The USBs are definitely working... things connected to them do light up... just the system doesn't do anything

Finally getting somewhere to figuring out what the issue is.... After resetting the RAM sticks, I finally managed to load up into the post screen after the motherboard splash screen where it tells you RAM,CPU, Harddrives connected ect.... It said "AMD CPU Unrecognized"

So either the CPU is dead, the motherboard or I need to somehow get to flash the bios to update it.... which i currently have no idea how to do with a USB flash drive... here are the bios updates, but when I download them their exe files.... not really bootable in that format

http://www.gigabyte.com/products/product-page.aspx?pid=3154#

@vackillers: It should tell you in BIOS which version you're running, but that board has had support for your CPU for over five years. Unless somehow you are running a BIOS revision older than that, I don't think that is your problem. Still sounds like a bad CPU, now more so than ever with the motherboard reporting the CPU isn't recognized.

You could look up the BIOS update procedure for your board and try it, I'm not familiar with the update procedure on Gigabyte boards though. I'm sure there are tutorials out there.