Skulltrail Overclocking
FUGGER and K|ngp|n in Las Vegas
Intel D5400XS Skulltrail motherboard
Dual Intel QX9775 quad core processors
Cooled by: Dragon F1 Extreme
EVGA 8800 Ultra SLI
Cooled by: Tek 9
Enermax Galaxy
Mushkin 2GB FB-Dimm
Mushkin 1GB FB-Dimm
Micron 2GB FB-Dimm
Installing
The board is EATX standard and there is very little room for clearance around the edges on most of the largest cases, this is a Gigabyte Aurora and I have less than a quarter inch clearance.
On the pic above you can see the sealing on the board to prevent moisture damage.
The CPU sockets have small sinks on the mosfets that do not clear some after market cooling products including the Zalman heat sinks that Intel sent out to reviewers.
I had to notch both plastic mounting brackets to get an unobstructed seat on the CPU. I also had to rotate the bracket from its natural position that allowed the lever to swing open and free the CPU, right now I have to remove the bracket to open the lever.
I also installed a pair of Danger Den blocks where I had clearance issues on both sockets. I had to hack saw the edges of both blocks and die grind the edge of the face of one of the blocks that hit against some caps that are too close and too high to the socket.
The socket itself is for XEON with 771 pins but the mounting Intel chose to use was for Socket 775 to better suite after market options in cooling so be aware that some intervention may be needed for best fit.
I found out that ICH9R RAID worked on Skulltrail, all I needed to do was load the new INF drivers and all is up to speed.
This is 4x 150GB Raptors in RAID 0, onboard controller.
Loading windows Vista with RAID is fine.
Memory configurations
Sequential
Single channel
Dual channel
Dual channel interleave
Quad channel interleave
All settable via bios if the memory is installed in the correct slot, if you install memory in channel A it will be set to dual channel interleave. If you space the ram one slot you will reboot to single channel with interleave. If you install all four slots you get quad channel with interleave.
For most of the tests dual channel with interleave will perform adequately but for the most demanding overclocked stress on cores you will want quad channel with interleave.
Memory voltage in bios, you can set voltages for memory and for the AMB(buffer) chip. Raising the AMB voltage yielded no gain in timing or speed.
We tested various modules for bus speed and timing options and here is what we came up with.
800Mhz Mushkin 1GB
800Mhz Mushkin 2GB Rev E
800Mhz Micron 2GB Rev F
667Mhz Micron 1GB
With the 1GB modules it allowed us to open the FSB to 430Mhz pretty easy and we ran some 3D benches with 425~427Mhz bus speed. None of the 2GB modules would allow us beyond 406Mhz.
The Mushkin 2GB modules would allow timing change of cas 4 if they were installed in channel A, I then could install the Micron in channel B and they would run at cas 4. If I install the Micron Ref F it will not post at cas 4, just in channel B.
All memory could run at 5-4-4-15 timing and that is what was used for the 1GB modules at 425FSB. We ran those two modules in channel A in interleave mode, that equates to dual channel with interleave.
The memory does get very hot and needs extra cooling for overclocking.
The north bridge has notches for a fan to be mounted and it runs very hot, hopefully a fan will be supplied with retail versions and even then I would still suggest more cooling here.
Overclocking
On (pro) air with the supplied heat sinks I reached a top speed of 4.4Ghz for multicore benches.
http://service.futuremark.com/compare?3dm06=4982582
Stepping up to water cooling pushing past 4.5Ghz is pretty easy and I think I will end up around 4.4Ghz @ 1.45v and keep the fans on low. Im getting used to the silence. I will have several more pushes on water over the next few weeks.
Under LN2 we reached 5.6Ghz and settled in around 5.55Ghz for the threaded benches. Bios allows 1.6v with .3 offset for a total of 1.9vcore but the droop at 5.55Ghz is around .05v with a swing of +- .04v. There is a droop option in bios as well.
The cores bugged out around -117c and trip the thermal code for shutdown and refiring was pretty good, no bugs were present when booting into windows at -110c.
We did have a problem when raising the pcie frequency, the max frequency settable in bios is 120Mhz.
Other than the lack of vcore the board ran perfect, minimal performance hit with dual channel vs quad channel, we got more out of FSB to hit the perfect Mhz.
Running SLI
Cooling the north bridge notes.The Intel Skulltrail motherboard cannot support 3-way SLI. Skulltrail motherboards use two NVIDIA nForce 100 chips as you correctly state below. These chips allow for a maximum of two GeForce cards to work together, enabling SLI between two GeForce GPUs such as the GeForce 8800 Ultra.
The nForce 100 chips also enable Quad SLI, but only with two GeForce GX2 cards. That is the only method of Quad SLI right now – a card that has two chips on it paired with another dual-chip card.
There is no Quad SLI with four individual discrete cards – that product does not exist. If you put four Ultras onto Skulltrail, you can only connect two of them (must be connected to the same nF100 chip), and can only enable SLI with one set of cards. You could use the other cards to drive extra monitors, but not overall performance.
The nForce 100 SLI MCP will NOT support 3-way SLI. This cannot change even with a driver/bios update.
- Nvidia
When pushing MCH voltage there are a few bugs that arise and some people may have run into without knowing what was going on. 1.4 ~ 1.6 without a really good fan will cause an error in memory bandwidth tests, the first sign is Everest locking up seconds after opening the program. I also noticed BF2 shutting down between map changes with a memory error. I switched over to watercooling on the north bridge and lowered the voltage, everything is running correctly. Ive been running a high FSB and pushing MCH was getting me there but needed a bit more when you apply more than .2v over stock pm the alu heat sink.
Results
Skulltrail at the top of the ORB
http://www.futuremark.com/community/halloffame
wPrime 32m and 1024m
http://www.hwbot.org
New WR Cinebench 10 x64
Thanks to Intel, EVGA, Nvidia, Mushkin, and Enermax for your support.
Many thanks to K|ngp|n for flying in from Detroit to blast a 160L tank of LN2 and bringing the custom pots and talent to make this possible.
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FB-Dimms have always been flaky buggers. 
Originally Posted by jimmyz
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