I've kind of backed in to this overclocking thing. I've had some issues with heat, BSOD and low frame rates while gaming, even with completely default settings.
I decided to run Prime95 on the stock config and came to find out that Prime's torture test failed within a minute or two on every core, in random order. RealTemp's 10 minute test usually got all four threads to die with rounding errors.
So I've started playing, with some good results I think.
However, I can't for the life of me get the RAM to OC to 1600.
The CPU is rock solid as long as I turn the memory multiplier down.
Here are my current best case settings running XP SP3:
Motherboard: Gigabyte Model: GA-EP43T-UD3L Rev#: 1.4 Bios Version: F9
Cpu: Intel Q8400 2.66G 1333
Ram: G.Skill Model/Part# F3-12800CL7D-4BGRM
*MB Intelligent Tweaker(M.I.T.)
Robust Graphics Booster -------------- : [Auto]
CPU Clock Ratio ---------------------- : [8x]
Fine CPU Clock Ratio ----------------- : [0.0]
CPU Frequency ---------------------: 3.2 Ghz
*Clock Chip Control
CPU Host Clock Control --------------- : [Enabled]
CPU Host Frequency (Mhz) --------------: [400]
PCI Express Frequency (Mhz) ---------- : [100]
*DRAM Performance Control
Performance Enhance ------------------- : [STANDARD]
Extreme Memory Profile --- (X.M.P.) --- : [Disabled]
(G)MCH Frequency Latch ---------------- : [Auto]
System Memory Multiplier -------------- : (SPD) [3.20B]
Memory Frequency (Mhz) ---------------- : 1333 1280
DRAM Timing Selectable ---------------- : (SPD) [Manual]
*Standard Timing Control
CAS Latency Time -------- 9 ---------- : [7]
tRCD ------------------- 9 ---------- : [7]
tRP --------------------- 9 ---------- : [7]
tRAS ------------------- 24 ---------- : [21]
*Advanced Timing Control
>>Channel A
Static tRead Value --------------------- : [8]
Channel B
Static tRead Value --------------------- : [8]
*Motherboard Voltage Control
>>CPU
Load-Line Calibration ----------------- : [Enabled]
CPU Vcore --------------- ?.????? ----- : [1.287]
CPU Termination --------- ?.???V ------ : [1.2]
>>MCH/ICH
MCH Core ---------------- ?.???V ------ : [1.24]
>>DRAM
DRAM Voltage ------------ ?.???V ------ : [1.6]
Everything else is set to [Auto].
So this is stable at 8x400 and 3.20B 7-7-7-21-2T and tRD 8. This gives me 8400+ GB/s and <63ns latency on Everest. The odd thing is that the values are nearly identical for Read/Write/Copy at 8450/8459/8681. Doesn't this seem strange?
I can also run stable at 8x400 and 2.66D 7-7-7-20-2T and tRD 8.
Dual booting into Ubuntu 8.x won't tolerate these settings. I have to clock down to 8x390 and 3.20B 9-9-9-24, which leaves my DRAM at 1248.
I cannot run stable with anything that leaves the DRAM at 1333 or higher.
The 3.00A strap failed miserably too, with BSOD at startup.
The only exception to this was CPU 8x367, DRAM all [Auto], MCH 1.18v, ICH I/O 1.650v, and DRAM 1.6v, leaving the RAM running at 1468. If I recall the MB selected 10-10-10-27, which is why I tried that below.
Trying to get to 1600, I've experimented with 3 of the 4 possible 4.00x straps. (One of the 4 is not selectable) at timings as slow as 10-10-10-27+. I've been as high as 1.34v on CpuCore, 1.24v on CpuTerm, 1.3v on MCH, 1.650v on ICH I/O (someone else's suggestion) and 1.62v on the DRAM.
I have swapped the RAM around and also tried moving from the 1/3 slot pair into the 2/4 pair of slots.
Any thoughts on getting to 1600?
Model of the motherboard: Gigabyte GA-EP43T-UD3L
Model of the memory: F3-12800CL7D-4BGRM
Model of the CPU: Intel Q8400 2.66
I decided to run Prime95 on the stock config and came to find out that Prime's torture test failed within a minute or two on every core, in random order. RealTemp's 10 minute test usually got all four threads to die with rounding errors.
So I've started playing, with some good results I think.
However, I can't for the life of me get the RAM to OC to 1600.

Here are my current best case settings running XP SP3:
Motherboard: Gigabyte Model: GA-EP43T-UD3L Rev#: 1.4 Bios Version: F9
Cpu: Intel Q8400 2.66G 1333
Ram: G.Skill Model/Part# F3-12800CL7D-4BGRM
*MB Intelligent Tweaker(M.I.T.)
Robust Graphics Booster -------------- : [Auto]
CPU Clock Ratio ---------------------- : [8x]
Fine CPU Clock Ratio ----------------- : [0.0]
CPU Frequency ---------------------: 3.2 Ghz
*Clock Chip Control
CPU Host Clock Control --------------- : [Enabled]
CPU Host Frequency (Mhz) --------------: [400]
PCI Express Frequency (Mhz) ---------- : [100]
*DRAM Performance Control
Performance Enhance ------------------- : [STANDARD]
Extreme Memory Profile --- (X.M.P.) --- : [Disabled]
(G)MCH Frequency Latch ---------------- : [Auto]
System Memory Multiplier -------------- : (SPD) [3.20B]
Memory Frequency (Mhz) ---------------- : 1333 1280
DRAM Timing Selectable ---------------- : (SPD) [Manual]
*Standard Timing Control
CAS Latency Time -------- 9 ---------- : [7]
tRCD ------------------- 9 ---------- : [7]
tRP --------------------- 9 ---------- : [7]
tRAS ------------------- 24 ---------- : [21]
*Advanced Timing Control
>>Channel A
Static tRead Value --------------------- : [8]
Channel B
Static tRead Value --------------------- : [8]
*Motherboard Voltage Control
>>CPU
Load-Line Calibration ----------------- : [Enabled]
CPU Vcore --------------- ?.????? ----- : [1.287]
CPU Termination --------- ?.???V ------ : [1.2]
>>MCH/ICH
MCH Core ---------------- ?.???V ------ : [1.24]
>>DRAM
DRAM Voltage ------------ ?.???V ------ : [1.6]
Everything else is set to [Auto].
So this is stable at 8x400 and 3.20B 7-7-7-21-2T and tRD 8. This gives me 8400+ GB/s and <63ns latency on Everest. The odd thing is that the values are nearly identical for Read/Write/Copy at 8450/8459/8681. Doesn't this seem strange?
I can also run stable at 8x400 and 2.66D 7-7-7-20-2T and tRD 8.
Dual booting into Ubuntu 8.x won't tolerate these settings. I have to clock down to 8x390 and 3.20B 9-9-9-24, which leaves my DRAM at 1248.
I cannot run stable with anything that leaves the DRAM at 1333 or higher.

The only exception to this was CPU 8x367, DRAM all [Auto], MCH 1.18v, ICH I/O 1.650v, and DRAM 1.6v, leaving the RAM running at 1468. If I recall the MB selected 10-10-10-27, which is why I tried that below.
Trying to get to 1600, I've experimented with 3 of the 4 possible 4.00x straps. (One of the 4 is not selectable) at timings as slow as 10-10-10-27+. I've been as high as 1.34v on CpuCore, 1.24v on CpuTerm, 1.3v on MCH, 1.650v on ICH I/O (someone else's suggestion) and 1.62v on the DRAM.
I have swapped the RAM around and also tried moving from the 1/3 slot pair into the 2/4 pair of slots.
Any thoughts on getting to 1600?
Model of the motherboard: Gigabyte GA-EP43T-UD3L
Model of the memory: F3-12800CL7D-4BGRM
Model of the CPU: Intel Q8400 2.66
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