Computer won't power on after RAM upgrade

Hi folks. Today I got 2 new 4GB sticks of Corsair Vengeance Blue RAM to go with the 8GB I already have in my system (same RAM as well). After all 4 sticks were installed, my computer failed to power on properly. It would power on for about 5-6 seconds then shut off, and continuously try to start up again, only to shut back down. I did have a few minor overclocks in place so I went into BIOS and reset everything back to default, but the computer still refuses to power on with all 4 sticks in place. I've tried different combinations of the 4 sticks and they all work fine as long as all 4 aren't hooked up at the same time. My PSU is 650W if that helps. I really doubt 2 additional sticks of RAM is making much difference in power usage. Any help would be appreciated.

Note: As to why I need/want 16GB of RAM, I play around with Photoshop + do some video editing in After Effects and Premiere, and I found myself maxing out the 8GB I had rather easily.

It supports up to 32GB.

Yah, I'd try tweaking the CL or even the speed itself, as bobkn has mentioned. Use this as a reference. You could look in your motherboard's manual to see if there are any weird limitations about using only two or four slots when using this or that amount of RAM. Other than that I'm at a loss.

Yah your PSU should be fine; RAM barely uses anything (maybe 5 watts a piece, or something). Although it would be ironic if you were just below that threshold with the two sticks, and the other two pushed it over, heh. Doubt it.

Have you run Memtest86+ on the RAM yet? You can test each stick individually in slot A1, or 2 at a time in the same channel.

RAM does use a relatively large amount of juice (in use). And it is common that populating all 4 slots requires a small boost in voltage on some motherboards to get them all fired up.

I would then suspect a bad slot. One common and simple problem can be dust or hair in the slot, particularly if has been empty for a while. You can inspect it closely, if you see any crud use compressed air to clean it out (never a pointy implement).

As the others zeroed in on

4 sticks of ram installed say of speed 1866 have to be clocked back one speed step in order to run

Seen this many times

2 sticks 8gb x 1866 would run fine (if motherboard/bios updates allow)!

Corsair Blue comes in CL 8, 9, 10 - have you double checked the sticks match?

Next thing I would do is reset bios - but you say you already did this. Try jumpering the bios pins on m/board to reset.

We are talking about the Vengeance RAM rated at 1600MHz, are we not? You mentioned they were the same as what you, I assumed, had listed in your specs, so we are talking about two 4GB sticks rated at 1600MHz, right? I hate being confused.

I'm seeing two 8MB pairs (2x4MB) at 1600MHz at 9-9-9-24, and another at 8-9-8-24. and mentions that they've been tested at 1600MHz, but makes it seem like its normal speed is only 1333MHz. And one of them (CMZ8GX3M2X1600C8B, as oppposed to the CMZ8GX3M2A1600C9B) mentions the CL tested at is 8-9-8-24 yet the "regular" speed is 9-9-9-24. I'd definitely say try manually setting timings.

And we are talking dual-channel, not quad or anything, right? Make sure we're talking about the right ones here, heh.

Please post the part numbers of all ram stick and the specs. The term (all ram is the same) means many things to many people.
You motherboard supports 32 gigs DDR 3, 1600 to 2133, 1.5 volts. Your motherboard is dual channel architecture.
GIGABYTE - Motherboard - Socket 1155 - GA-P67X-UD3-B3 (rev. 1.0)

Also check your motherboard manual to see if their are any jumpers that need to be put in any particular fashion for 16 gigs of ram.

I had similar issue's when adding 4gb or Corsair xms3 to a kit of the same i already had. No matter what i did it would'nt play nice and kept showing different amounts of usable ram. It turned out that the 2 kits had different version numbers.
The 2 kits also had totally different spd info embedded.

Have you checked if the kits are the same version?

Just my 2 cents