OC NOOBIE,
First welcome to the forums and your very first post here.
I think the main factors for getting good overclocking results are:
1. A good, selective set of hardwares.
2. Luck in getting some highly overclocking components, mainly CPU, memory, motherboard and (video card).
3. Careful observation, detailed analysis of results, and (patience).
I think your hardware set is very similar to what I use, they are a good set to begin with. Your memory is TCCD based (I think), which is good for tweaking NF4 boards over a wide range of frequency and timing, low voltage compared to BH-5/UTT. The DFI NF4 board is also very flexible for memory tweaking and selection of voltage range (way more than needed).
The 3006 MHz is just for system posting, boot and getting into memtest. The system can boot into windows at 2.95 GHz. Run SuperPI 1M at 2.9 GHz. SuperPI 32M at 2.85 GHz. Prime95 stable at 2.73 GHz. So there is the common frequency span of 200 - 300 MHz between highest CPU boot and stable Prime95.
I think I may have been lucky to get all the CPU, memory and motherboard in one shot which can perform so well. Let me suggest what I may try from what you described.
1. My G. Skill 4400 LE can run ~310 MHz 2.5-3-3-7 1T 2.8 V and up to 350 MHz 3-5-5-10 1T 2.8 V. If you have set your timing correctly and is still getting 290 MHz, apparently your OCZ rev2 platinum is not as overclockable.
But first, try to set all extended timing to AUTO (or use latest official bios 03/10/05 which defaults them to AUTO, with max async latency to AUTO), and confirm with memtest that indeed 290 MHz 2.5-4-4-7 1T is the max of the memory. Don't worry about setting those extended timing to AUTO until finding the max for CPU, memory. Tighter extended timing may help to get a point or two in benchmarking (later). If some of the extended timings are set too tight as in your list (e.g. max async latency = 7), it may hinder your max memory frequency which also determines you max HTT and CPU frequency (unless you go into using memory_HTT_ratio other than 1).
DRAM Bios Setting (for TCCD) bios 02/17/05
DRAM Bios Setting (for TCCD) bios 03/10/05 @ 315 MHz
This is the very first thing you need to determine, the max memory frequency and the associated timing. If you have access to another set of memory modules, try them too.
2. As for CPU, the 90 nm Winchester is a very tricky piece of silicon, it requires a low enough amount of voltage for finding a given stable frequency. With just the right amount of voltage, it can run cool and fast. But do not over-apply voltage to it, as it would generate unnecessary heat and hot spot due to leakage current and in turn create unnecessary instability and slow down. I found that for my setup, 40 C max on air, 1.5 - 1.55 V is the right balance of temperature and voltage. Anything higher than that would add instability.
Try to lower your CPU voltage as much as you can to look for a given frequency.
What is the load and idle CPU temperature?
What are the highest CPU boot, post, OS boot frequencies and voltage?
Try to find out what is the max CPU frequency at 1.4 V.
Bare minimum voltage at maximal overclocking
3. In my setup, chipset voltage = 1.5 V, LDT voltage = 1.2 V, raising them does not help.
4. Try to set LDT multiplier to x3 explicitly to avoid uncertainty (you set it to 4). Setting it to AUTO should be OK too, but not as safe as x3 during testing.
5. Run SuperPI 32M, 3dmark 01/03 for quick CPU, memory and system stability test.
6. If Prime95 fails, use the different options to diagnose:
Prime95 small FFT is mainly for testing CPU.
Prime95 large FFT is mainly for testing CPU and memory.
Prime95 blend is most difficult to pass as it involves chipset, system bus in additional to CPU and memory, and its run is most susceptible to background processes, hard drive activities, paging, voltage fluctuation, ....
SuperPI 32M is a relative "quick" way to test CPU and system speed and stability
Stability testing using memtest, SuperPI (32M) and Prime95
7. I am not familiar with your PSU, hope it is fine. Do not overclock your 6800 GT while searching for optimal CPU, memory and motherboard operating points.
That's it for now, may add more later. Hope these help.