F2-8500CL5 2x1GB errors on ASUS P5Q

[rhiebert]

MB: ASUS P5Q (BIOS 1501 & 1406)
RAM: F2-8500CL5 2x1GB
CPU: E8200 (8x333MHz)
Video: ASUS Silent HD3650
OS: XP SP3
Cooling: 4 fans temperature controlled;
Memory sticks run slightly warm to touch.

MemTest Version: 3.8
Memtest+86 v2.10
800 & 1066 MHz Default settings:
Memory Voltage: 2.1V
Settings are: 5-5-5-15; rest at auto

Problem: I am unable run this ram at 800MHz or 1066MHz without MemTest errors.

I have done a number of experiments like switching ram to slot's 1 & 3; setting FSB voltage up to 1.4V; increasing NB voltage up to 1.3V; trying different FSB straps; increase
Vcore; manually set memory timings;

I changed the BIOS back to version 1406. Same problem.

Then I ran memtest86+ as follows:
1. Slot 0 & 2 at 1066 MHz: failed
2. Slot 0, One stick: S/N 475 passed 1 pass
3. Slot 0, One stick: S/N 476 failed
4. Boosted Memory voltage to 2.2V, FSB=333/FSB=1.28V, NB=1.26V
- Slot 0, One stick: S/N 475 passed 1 pass
- Slot 0, One stick: S/N 476 failed
5. Same setting as 4: Slot 1 & 3: failed in 2nd pass

When I initially set up my system in July I was able to run Prime95 stablily for 6 hous with a 3.58GHz OC (Vcore:1.36V) & 1069MHz Ram (2.1V,FSB=333,NB=1.3V). These settings no longer work and I have narrowed the problem to memory errors.

Any suggestions would be helpful. Is there reason to believe I may need to go back to an even earlier version of the BIOS?

[G.SKILL]

it seemed one stick is defective
did the one with S/N 476 work fine in single channel at DDR2 1066?


G.S

[rhiebert]

The S/N 476 stick did not pass single channel at 1066 MHz.

Over the weekend I tried a few more radical settings:
1. Bumped Memory Voltage: 2.2V
Still had failure with S/N 476 at 1066 MHz.

2. Memory Voltage: 2.2V; Changed NB clock delay from AUTO up to 800ps (does not pass below 600ps delay).
At 800ps delay I was able to run memtest through 10 full cycles at 1066MHz with both sticks installed. Is 2.2V acceptable for long term operation or should I just RMA the stick(s) and call it a day?

[G.SKILL]

we'd recommend you to return to us for RMA, 'coz it couldn't run at rated speed
thanks


G.S