First, I built this system almost 2 years ago. Started with just 4GB of RAM. Everything has ran fine and still does. Last fall I was building a friends system, and I started looking for RAM. It was impossible to find my RAM. Eventually I bought a used set from overseas, got it installed and started doing some testing. Everything was working fine. I ran MarkVantage and my initial score was P17202. I noticed that my RAM was showing up as 533 MHz on the FSB on each stick of RAM with timings of 7-7-7-16. I knew that the specs were 1600 for that FSB, and timing should be 7-7-7-24; so I started digging. My original quest was just to get my RAM to run at the boasted FSB/timings.

I Flashed my BIOS to P10, which is the current BIOS. MarkVantage Score up to P17202.

I then adjusted my timings to 7-7-7-24, score up to P17295.

Next, I updated the FSB, I did the following:
FSB-Mem clock Mode from Auto to Unlinked
FSB-(QDR), MHz 1333-> 1600
MEM(DDR) MHz 1066-> 1600
Reset Memory Voltage to 1.9v
CPU Core [1.35625]
CPU FSB [1.35]
nForce SPP [1.45]
nForce MCP [1.6]

GTLVREF Lane 0 [AUTO]
GTLVREF Lane 1 [AUTO]
GTLVREF Lane 2 [AUTO]
GTLVREF Lane 3 [AUTO]

This resulted with a surprise, 3400MHz or 3.4 GHz Over Clock. Score up to P17880.

All seemed to work great, I was very happy with my blunder. Then after a couple weeks, my system started to crash on restarts. Not every time, just every so often. The MOBO would reload my original bios in Safe mode and restart. Worked great though when I got it restarted. Ran Prime95 for 3 hours straight while watching a movie, no errors, max temp was I think 62C. Still crashed every few restarts.

So, I followed this guide for a stable system: [link=../forumsarchive/tm.asp?m=499530]http://forums.evga.comarchive/tm.asp?m=499530[/link]
 
Here are my current settings:
**System Voltages**
FSB-Mem clock Mode [Unlinked]
FSB-(QDR), MHz 1333-> 1600
MEM(DDR) MHz 1066-> 1600
Reset Memory Voltage to 1.9v
CPU Core [1.35625]
CPU FSB [1.35]
nForce SPP [1.45]
nForce MCP [1.6]

GTLVREF Lane 0 [AUTO]
GTLVREF Lane 1 [AUTO]
GTLVREF Lane 2 [AUTO]
GTLVREF Lane 3 [AUTO]

**System Clocks**
CPU Freq, MHz: 3.4 GHZ
FSB Reference Clock, MHz: 1600
CPU Multiplier: [8.5X]
CPU N /2 Ratio [Enabled]
PCle x16-1 & 16-2, MHz: [100]
PCle x16-3, MHz: [100]
SPPc->MCP Ref Clock, MHz: [200]
nForce SPP --> nForce MCP: [5X]
nForce SPP c-- nForce MCP: [5X]

**Spread Spectrum**
CPU Spread Spectrum: [Disabled]
HT Spread Spectrum: [Disabled]
PCle Spread Spectrum (SPP): [Disabled]
PCle Spread Spectrum (MCP): [Disabled]
SATA Spread Spectrum: [Disabled]

**FSB & Memory Config**
FSB - Memory Clock Mode: [unlinked]
FSB - Memory Ratio: Auto
FSB (QDR), MHz: [1600]
Actual FSB (QDR), MHz: 1600
x MEM (DDR), MHz: 1600
Actual MEM (DDR), MHz: 1600
P1: [AUTO]
P2: [AUTO]

**Memory Timing Setting**
Memory Timing Setting: [Expert]
tCL (CAS Latency): 8
tRCD: 7
tRP: 7
tRAS: 24
Command Per Clock: [2T]

**Advanced Memory Settings**
tRRD [AUTO (6)]
tRC [AUTO (40)]
tWR [AUTO (12)]
tWTR [AUTO (16)]
tFAW [AUTO (25)]
tREF [AUTO]
tRFC [88]

**CPU Configuration**
Limit CPUlD Maxval: Disabled
Intel Speedstep: Disabled
xPPM Mode: [Native]
CPU Thermal Control: [Disabled]
C1E Enhanced Halt State: [Disabled]
Execute Disable Bit: [Disabled]
Virtualization Technology: [Disabled]
CPU Core 0: [Enabled]
CPU Core 1: [Enabled]
CPU Core 2: [Enabled]
CPU Core 3: [Enabled]
 
Tried to start it, exact same problem. Just nothing...., I hit reset, it fires up in safe mode with default settings, went to bios, F10, ... perfect restart. I tried to set the timings at 7.7.7.24, and it would not start.  Tried to move them to 8.7.7.24 and it started, but still crashed after a few restarts.

I was also chatting with a friend, he told me someone he knew had the same problem, and it was his PSU. This sounds like it could be the problem. I never ran the tests before getting the additional RAM. So maybe the extra draw from them with the high power draw on the CPU from the tests, is causing the power supply to need reset?  I called Ultra, they agreed, and I sent that PSU back to be replaced.  In the mean time, I am running a 65a Cooler Master 800 w silent pro gold.  It is about 90% efficient at full load.  Same problem, so not the PSU.
 
Please help, I no not where I am going wrong!

Yea, I have ran all the memtest86, all good there.
I actually have not had any tests fail.  It went through 24 passes on IBT extreme settings, Passed Occt, did Prime95 for 3 hours while watching a video, all good.
 
I will try your settings and post back.  It normally takes a few restarts to a few days before the crash happens again.

OCZ RAM is known for not agreeing with the 790i chipset.  I would manually set the timings that auto supplied for the RAM.

I don't get any codes, I just get a blank black screen.  It happened again this morning before I made the change from AUTO to the settings that auto  gave me.  This morning, from a cold start, I started, and black screen, no boot.  I loaded bios, I made the changes VistaHead said in post #5,  I set the RAM to Expert, and manually entered all the specs in both timings and advanced timings, and I bumped the V to 2.0 from 1.9.
 
Now, I booted right up again at 3.4 at 1600, I passed IBT with no issues, also ran 3D Markvantage, score was 19544.
 
Leaving for work now, I am going to put the computer to sleep, and see if it will wake up without reloading my settings.
 
Is there a place I should be looking for this code you mentioned?

Well it crashed again.  I did manage to get a code I think.  I wasn't watching, but rebooted, and black screen, I pulled off the cover and E2 was on the LED display.  Thanks for pointing that out.
 
I hit reset and it would not restart, after a couple pushes, I got the FF on the display.  Had to turn off PSU, and it restarted with the defaults. 
 
I was actually smart enough to turn on the Minidump feature.  I can't figure out how to open it, but I have the file.  I have a three dumps in total over the last month.  How do I open those? 

To the Moderator that awarded me the BR's....thank you, they are appreciated!

Do you have the Performance feature installed?  Most folks use AIDA64 Extreme to monitor all temps.  Should you use it, after installation, click Computer - Sensors, your temps will be there.  http://www.aida64.com/downloads

Have you tried uninstalling and reinstalling your GPU drivers?

A few thoughts:
1.  The gray slots are rated up to 1800Mhz, the black slots 2000Mhz.  Many folks are running 8GB of RAM at high overclocks (see JeffreyHam, for one).
2.  You hit the nail on the head when you stated OCZ RAM does not play well with the 790i chipset for everyone.  It is hit or miss.
3.  To solve your issues, replace the OCZ RAM.