Overclocking optionsDFI boards are made for overclocking, so the next little screen called "Genie Bios settings" will no doubt become your best friend very quickly:
Let's explore the options on the "Voltage control" screen first:
On the above thumbnails you can find :
Overview of the "Voltage Control" screen
CPU "VID" Control up to 1.60 Volts
CPU "VIDSpecial Add" up to 121.25%
DDR2 "DRAM Voltage Control" up to 3.04 Volts
Northbridge "Core Voltage" settings up to 1.74 Volts
Particular about DFI’s processor voltage controls remains the limited direct control you have over the CPU voltage. A maximum of 1.60 Volts might not seem a like a lot for the demanding overclocker, but that's where the "special add" control comes to help. Theoretically this means you can provide up to 1.944 Volts to the CPU., which means you will need some pretty serious cooling for your processor (that would be liquid nitrogen or LN2 ;-) ).
Furthermore, please remember that the JEDEC's specifications for DDR2 memory are something like 1.8 Volts... This means that putting 3.04 through your DRAM modules might shorten the lifespan rather dramatically. Voltages up to 2.2-2.4 Volts should be safe depending on the memory chips you are using, but please be careful. Finally, the Northbridge or 680i chipset is very (in)famous for being extremely hot already at its stock voltage of 1.3 Volts. I measured the temperature of the chipset once on an Asus board, without active cooling, and the chipset reached over 100°C already. Anyway, when you're planning to do some overclocking while increasing the Northbridge voltage, make sure to add that 80mm fan to the heatsink that is supplied with the motherboard.
Anyway, please regard the above paragraphs as a "proceed at your own risk" warning, and don't go about doing crazy stuff unless you know what you're doing.
Have a renewed look at the bottom section of the voltage page:
Of particular interest in the above screen is the highlighted number, and the two numbers below it. These three numbers represent the "GTL ref voltage control", which represent in my opinion the most revolutionary bios settings since the introduction of the latency controls of SD-Ram. To give an exact explanation of the nature of this bios settings would lead us much too far, and other - more intelligent - people have done their best to provide us with an in-depth analysis of GTL or Gunning Transceiver Logic reference voltages. A must read in this respect is the article by Kristopher Boughton, better known as FreeCableGuy (FCG) and as such co-founder of The Tech Repository. This was actually the first time that Gunning Transceiver Logic was made accessible to the public, by explaining exactly what it can do for you.
The most important fact of the above screen is however that only DFI, and DFI only, delivers control over these voltages in their standard bios. The first time these controls were introduced was with a previous Intel DFI board : the DFI ICFX3200-T2R, the only RD600 board that ever hit the market. It is here that the genius of Oscar Wu surfaced once more, as it was he who found out the impact of the GTL reference voltage on the overclocking of CPU's, especially quad core CPU's. Quad core cpu's had proved to be a front side bus nightmare since they were introduced late 2006. Whereas the Conroe (and Allendale) cpu's proved to be excellent front side bus overclockers on all but the most basic motherboards, reaching over 400 front side bus on almost all occasions, quad core cpu's were a very different story. On all but a few lucky exceptions, reaching 400 front side bus was next to impossible. Especially the 680i and 975 chipsets - the ones that many high end users cater to - had lots of problems with the quad cores. Since the introduction of GTL reference voltages now, things have changed...
Next question that comes to mind of course is : how should I use GTL ref voltages ? To answer this question, I'd like to point again to The Tech Repository, but this time to the other Co-Founder : Tony "Bigtoe" Leach. Tony has been working closely with DFI over the last months and has brought to us the definitive guide of the ICFX3200, including a how to on GTL voltages. And before you ask, yes, there is a guide to the DFI 680i LT as well. As soon as the board hit the streets, Tony has provided us with a preliminary setup guide, again explaining how to go to work with quad cores and GTL voltages.
Now let's have a look at the final 4 screens of the voltage section:
These thumbnails address the following voltages:
Southbridge Dual voltage tuning : 1.52 up to 1.83 Volts
LDT voltage control : 1.22 up to 1.57 Volts
CPU VTT voltages : up to 1.60 Volts
Southbridge Coe voltage : up to 1.82 Volts
The Southbridge (or MCP) is cooled by DFI's "flat" fan ensemble which leaves the necessary room for PCIe cards in SLI. However good this little fan is, be careful when you crank up the voltages to the Southbridge. The exact function Southbridge dual control is up until now undocumented, and unknown. During testing I found no positive (or negative) effects of the tuning of the Southbridge dual control. The CPU VTT voltages are a different story of course, and in this case very narrowly connected to the GTL ref voltages, for quad cores anyway. For further reference, please visit the TTR guide I mentioned. The LDT voltage control is the voltage control for the bus speed between Northbridge (SPP) and Southbridge (MCP). This voltage only needs to be raised when you OC this bus past the standard 1000Mhz (200x5).
Front Side Bus tuning
The second screen of the "Genie Bios settings" bios page is the “Front Side Bus (FSB) & Frequency Setting” sub page. This page looks like the first thumbnail below. The idea of this page is to overclock the front side bus and memory frequencies, in order to increase CPU speed and bus bandwidth. The other thumbnails provide a close-up of the different options available:
The following options are displayed on the three remaining thumbnails above:
Front side bus frequencies from 800Mhz up to 2500 Mhz (quad pumped)
Memory frequencies from 400Mhz up to 1400Mhz (DDR or Dual Data Rate)
LDT bus or SPP <-> MCP bus frequencies from 200Mhz (standard) up to 500Mhz.
The standard front side bus frequency depends on the installed processor : an older Pentium D8xx for example would have a quad pumped frequency of 800Mhz (or 200Mhz bus speed), the current lineup of E6x00 cpu's have a 1066Mhz quadpumped bus, the recently introduced E6x50 cpu's have a faster 1333Mhz quad pumped bus. The DFI board fully supports the cpu's with 1333Mhz bus speeds, as you can see in the board's specifications as well.
Memory speeds can be adjusted from 400Mhz DDR up to 1400Mhz DDR. This 1400Mhz was a slight letdown to me, as I've reached 1300Mhz DDR easily on older boards, with reasonable voltages. As the voltages can be raised rather dramatically, I would think 1500 or 1600Mhz DDR would be a viable option. Anyway, as we'll see later, the 1400Mhz will prove more than enough.
Most important aspect of the memory subsystem is something that was covered extensively already throughout the review community: unlinked memory clocking. With the exception of the ATI RD600 board, all older chipsets do not have the possibility to clock the memory independent from the cpu's front side bus. A couple of dividers are present on all boards, like (cpu-bus:mem-bus) 1:1, 4:5, 2:3 or 1:2, but the options were very limited. nVidia tried to change that with the 680i chipset. Although memory clocking is still not completely independent (contrary to the ATi RD600 where it is), nVidia has locked a whole bunch of dividers into the chipset, providing near independent memory clocking options. When playing with the "unlinked" memory option in the bios, you'll notice that the memory numbers shift slightly when you adjust the cpu's front side bus. These are the different multipliers that are changing to provide you with a memory speed as close as possible to the one you are requesting.
Finally, we've got the LDT bus overclocking, which would improve speeds between North and Southbridge. When doing so, remember to adjust the voltage of the LDT bus accordingly, as we mentioned before.
The final three thumbnails of the frequencies page display the following:
LDT bus multiplier setting (1 to 5)
CPU multiplier setting (for the installed cpu 6 up to 10)
CPU Bselect setting (settings 1 up to 7)
The LDT bus multiplier should be viewed in combination with the bus frequency setting of the previous thumbnails. This is a setting which resembles the AMD hyper threading bus settings a little: for normal operation you should keep bus speed x multiplier at approximately 1000 (Mhz), therefor the standard setting is 200Mhz x multiplier 5.
The CPU multiplier is of course a very important setting, and was not functioning very well with the early biosses. In this case, an unlocked QX6700 processor was installed, but the CPU was not actually unlocked using this bios version. Things have been corrected very quickly though, and more recent biosses have no problems at all with adjusting multipliers downwards for all (Conroe and Kentsfield) cpu's, and upwards for the "extreme edition" cpu's.
Finally, the CPU B-select feature is something entirely new as well. More research has to be done to see which settings provide the best OC possibilities, for now I'd like to point to Tony's guide again, which explains the basics. All in all, it seems that Oscar Wu has programmed this setting quite well for most cpu's, so the "auto" setting is your best bet.
Memory tuning
Finally, a last very necessary bios page is the "memory timing setting" page which lets you control the main latencies of the memory:
Important to know here is that you've got a standard setting, where the board controls the memory timings, and an expert settng, which lets you take control of things. This page is certainly not the most extensive memory tuning page I've ever seen (nForce 4 did much better here), but the main options (and a little more) are there. It's certainly enough to confuse the novices among us. Most important feature on this page is the "Command per clock" setting which lets you choose between a setting of 1 cycle or 2 cycles. This feature has not been present on Intel chipsets, and should provide a healthy speedup of the ram subsystem. But more on that later...
Time for some testing ->
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