EP45-DS3L: Almost there, what next

[CrispyCritter]

Many thanks to the folks on this forum - I'm new to overclocking and I've spent many hours here reading and getting introduced to it! I'm almost there (I think) - prime is now failing after running for hours. A couple of questions.

System:
Motherboard - EP45-DS3L (F10)
Memory - 4GB (2x@GB) OCZ Platinum Vista Upgrade DDR2 PC2-6400 http://www.ocztechnology.com/product...m_dual_channel
CPU - E8400
Arctic cooling Freezer 7 pro.
Antec 1200 case
Corsair 750 watt power supply
cheap low power video card
12 TB Sata disks

System is for academic research - goal is to reduce an upcoming 15 day CPU time experiment by several days. System is running Linux (Fedora 10).

Questions:
1. What other good linux tools should I be using? At the moment I'm using
memtest86+ (v2.10) boot CD
mprime (prime95) torture test
lm_sensors for temp and voltage
2. I'm still not clear on the implications of using, for example, system memory multiplier of 2.00D as opposed to 2.00B. My understanding is that strap D should be used if it works, but B is more forgiving. Is that right?
3. I'm seeing large temperature differences from minor changes to Vcore. Going from 1.200v to 1.225v has decreased the temperature from 67 to 55 under mprime torture load. I was not expecting that at all; is it reasonable?
4. Here's my current settings (mprime has been running an hour on them so far). Does anyone have suggestions (very vanilla settings for a 3.0 -> 3.96 overclock at the moment).

MB Intelligent Tweaker(M.I.T.)
Robust Graphics Booster ...............: AUTO
CPU Clock Ratio ..........................: 9X
Fine CPU Clock Ratio.....................: +0.0
CPU Frequency ...........................: 3.96GHz

Clock Chip Control Standard Clock Control
CPU Host Clock Control..................: [Enabled]
CPU Host Frequency (Mhz) ............: 440

PCI Express Frequency (Mhz) .........: 102
C.I.A.2 .................................:[Disabled]

Advanced Clock Control [Press Enter]
CPU Clock Drive...........................: 800mV
PCI Express Clock Drive.................: 800mV
CPU Clock Skew (ps)....................: 0ps
MCH Clock Skew (ps)...................: 0ps

DRAM Performance Control
Performance Enhance...................: [STANDARD]
(G)MCH Frequency Latch...............: [Auto]
System Memory Multiplier ..............: 2.00D
Memory Frequency (Mhz) ..............: 800 880
DRAM Timing Selectable ................: [Manual]

Standard Timing Control
CAS Latency Time........................ 5
tRCD ......................................... 4
tRP'........................................... 4
tRAS.......................................... 15

Advanced Timing Control
tRRD........................................... 3 Autot
WTR.......................................... 3 Auto
tWR............................................ 6 Auto
tRFC...........................................54 Auto
tRTP........................................... 3 Auto
Command Rate (CMD) ....................:0 Auto

Driving Strength Profiles
Driving Strength ............................
Channel A
Static tRead Value.........................:11 [Auto]
tRD Phase0 Adjustment...................:0Auto
tRD Phase1 Adjustment...................:0 Auto
tRD Phase2 Adjustment .................:0 Auto
tRD Phase3 Adjustment..................:0 Auto
Trd2rd(Different Rank)....................:6 Auto
Twr2wr(Different Rank)...................:6 Auto
Twr2rd(Different Rank)...................:5 Auto
Trd2wr(Same/Diff Rank)..................:8 Auto
Dimm1 Clock Skew Control...............:Auto ps
Dimm2 Clock Skew Control...............:Auto ps

Channel B
Static tRead Value.........................:11 Auto
tRD Phase0 Adjustment...................:6 Auto
tRD Phase1 Adjustment...................:Auto
tRD Phase2 Adjustment .................:Auto
tRD Phase3 Adjustment..................:Auto
Trd2rd(Different Rank)....................:Auto
Twr2wr(Different Rank)...................:Auto
Twr2rd(Different Rank)...................:Auto
Trd2wr(Same/Diff Rank)..................:Auto
Dimm1 Clock Skew Control...............:Auto ps
Dimm2 Clock Skew Control...............:Auto ps

Motherboard Voltage Control
Voltage Type.………... Manual
CPU
CPU Vcore….……….........................: 1.2250V
CPU Termination…..... 1.200V*.......: Auto
CPU PLL…………………....1.550V*.......: Auto
CPU Referen.…………....0.805V*.......: Auto
MCH/ICH
MCH Core…………….....1.100V...........: Auto
MCH Reference….…….0.760V...........; Auto
MCH/DRAM Ref.…......
ICH I/O……………….....1.550V............: Auto
ICH Core…………...…

DRAM
DRAM Voltage ……....1.900V............:
DRAM Termination

Advanced Settings
Limit CPUID Max. to 3.....................: [Disabled]
No-Execute Memory Protect............: [Enabled]
CPU Enhanced Halt (C1E)................: [Disabled]
C2/C2E State Support....................: [Disabled]
x C4/C4E State Support..................: [Disabled]
CPU Thermal Monitor 2(TM2) ...........: [Enabled]
CPU EIST Function.........................: [Disabled]
Virtualization Technology................: [Enabled]
Integrated Peripherals
Legacy USB Storage Detect ..............[Enabled]


Following guide procedures to determine max memory speed (undermultiplying CPU), things seemed to be much more insensitive than everything I've been reading. Memory speed of 924 was fine for short tests, memory speed of 933 would eventually freeze memtest (often after 10 minutes), and anything above wouldn't post (speed would revert to either 800 or 933). Didn't matter what the voltage was or what the memory timings were. I don't see any reason I would ever need to exceed 900 with my setup (is there one?), so I didn't fine tune any more.

The Arctic cooling freezer 7 was definitely required. The "Instant gratification" settings sent the temperature up to 82 (under torture load) with the stock CPU cooler, but only 57 with the Arctic 7. (And as I said, I'm now at 55 with a much more substantial overclock (33% instead of 10%) after adjusting Vcore.

Any suggestions as to what to attack next? Settings above failed after 2 hours of mprime.
Thanks

[CrispyCritter]

Re: EP45-DS3L: Almost there, what next

Being suspicious of my lack of problems with memory at very high speeds, I ran memtest overnight at lower speeds and discovered that indeed I had problems. I had 8 errors in 8 hours. This was
FSB 295
CPU mult 6 (CPU speed 1770)
mem mult 3.00A (Mem speed 885)
everything else baseline settings.

All errors were in memtest test 5, all were the same bit in two different "clusters" of memory (most 10-20 MBytes difference). Several full passes had no errors at all.

Note that my "finger probes" of the memory and ICH10 cooler never got anything other than "pleasantly warm". There was just no heat building up - perhaps due to the number of fans
in the setup.

Evidently the overclocking guide instructions of running the first 3 tests weren't sufficient to tell enough for my particular memory. So my plan is to repeat my "guide" memory investigations, running only test 5.
Anything else to try? Should I be using a different strap in my tests? I used strap A since it was the only one with a 3.0 multiplier, trying to follow the sticky P35 guide as much as possible. (The only real problem in the P35 guide I had was trying to figure out how to adapt it to the P45 straps and memory multipliers - that took a while!)
Chris