DFI UT P35-T2R: Tweakers Rejoice!
by Rajinder Gill on October 18, 2007 2:00 PM EST- Posted in
- Motherboards
Quad-Core, Part 3
Finding stable VTT/GTLs @ 3.6GHz with G0 stepping quad-core CPUs
Assessing a motherboard's quad-core overclocking capabilities is best done at settings which are not at the extreme limits of attainable performance. The primary reason for this is because GTL settings become ever more sensitive to one digit (0.01v) changes as we near the maximum chipset capabilities. Our experience shows that 440-450FSB on this board is a good reference/starting point, as all chipsets should be capable of attaining this level of FSB with current G0 stepping CPUs, using a "relatively minor" (minor in terms of GTL tuning) amount of tweaking. Pushing high FSBs too soon is likely to bring mixed results, without attaining sufficient user understanding to make improvements when failures are experienced.
Although there is no adherent logic that can be applied to making GTL adjustments (without a scope), having a scale does give us the chance of some success. A safe point for starting out is around 400-440FSB using around 1.4V-1.5V VTT and appropriate GTLs. This will allow the user to get a feel for VTT/GTL change requirements as the FSB speed is scaled upwards. Below is the approach we used to get our foot in the door;
Recommended Overclocking Base Settings and Components
After entering target timings and voltages in the BIOS, we begin with some Prime95 testing in order to determine the effects of applied VTT/GTL adjustments. At this point we should already have determined sensible timings for RAM, which should not induce failures while we are checking for FSB stability. Sticking below default memory timing specifications while using specification voltage is a very wise choice at this point (use enough voltage for the RAM to run its specified speeds). We probed actual VDimm levels with a DMM to ensure that BIOS set values are not adrift from user set BIOS values. We could not find any significant level of voltage droop/undervolting/overvolting under idle or load conditions.
Our recommendations in terms of RAM are that you choose a good kit that can run at least DDR2-1066 @ CAS5. (2GB or 4GB of OCZ CAS5 PC9200 RAM has proven very successful with the 913 BIOS.) This will push towards the best performance possible from this board. At this time the P35 Chipset seems to favor Micron D9GMH based modules over the highly regarded D9GKX bin. A reason for the preference of the lower bin is unknown at this time. Our D9GKX modules required higher levels of voltage than we were accustomed to providing them, and we were not able to match the D9GMH based module results in terms of speed, stability, or timings ranges. The advantage to the user is of course good performance for less money, as D9GKX based modules are typically more expensive than their lower binned counterparts.
Lower speed-binned RAM is usable by adjusting strap/divider/FSB combinations in BIOS, to stay within RAM capabilities at the expense of overall performance. Tests between FSB and chipset strap ratios show the performance penalty in real world applications and games benchmarks is very small.
Of paramount importance is a level of patience and perseverance. GTL tuning takes time but can be very rewarding in terms of performance advantages. Again, perseverance is the key! Now, this is what we did to help determine which settings to change.
Remember up to the 913 BIOS the actual GTL core functions are mislabeled. The actual core each function relates to is shown below:
CPU GTL 1/3 REF Volt = GTL ref 0/1 (Cores 0 and 1)
CPU GTL 0/2 REF Volt = GTL ref 2/3 (Cores 2 and 3)
Finding stable VTT/GTLs @ 3.6GHz with G0 stepping quad-core CPUs
Assessing a motherboard's quad-core overclocking capabilities is best done at settings which are not at the extreme limits of attainable performance. The primary reason for this is because GTL settings become ever more sensitive to one digit (0.01v) changes as we near the maximum chipset capabilities. Our experience shows that 440-450FSB on this board is a good reference/starting point, as all chipsets should be capable of attaining this level of FSB with current G0 stepping CPUs, using a "relatively minor" (minor in terms of GTL tuning) amount of tweaking. Pushing high FSBs too soon is likely to bring mixed results, without attaining sufficient user understanding to make improvements when failures are experienced.
Although there is no adherent logic that can be applied to making GTL adjustments (without a scope), having a scale does give us the chance of some success. A safe point for starting out is around 400-440FSB using around 1.4V-1.5V VTT and appropriate GTLs. This will allow the user to get a feel for VTT/GTL change requirements as the FSB speed is scaled upwards. Below is the approach we used to get our foot in the door;
Recommended Overclocking Base Settings and Components
- Intel Quad-core CPU - G0 stepping
- A sturdy and proven PSU: we used the OCZ ProXStream 1000W for the majority of our testing
- High quality DDR2: you generally want RAM that is capable of CAS4 operation at DDR2-1100 with speeds up to DDR2-1280+ at CAS5
- High performance GPU: one that is capable of withstanding high PCI Express speeds such as the NVIDIA 8800 GTX Ultra
- Good Cooling: Thermalright Ultra-120 (with high CFM fans in push/pull) or very good water-cooling (i.e. Swiftech Apogee GTX/D-Tek Fuzion block)
- High Speed 80-120mm fans: used to cool NB/PWM and RAM
- Microsoft XP SP2 for 2GB or Vista 64-bit for 4GB Memory configurations
- Target CPU VCore is 1.37V-1.43V for 450FSB @ 3.6GHz. (Good cooling is required!)
- Target VNB is 1.55V-1.65V
After entering target timings and voltages in the BIOS, we begin with some Prime95 testing in order to determine the effects of applied VTT/GTL adjustments. At this point we should already have determined sensible timings for RAM, which should not induce failures while we are checking for FSB stability. Sticking below default memory timing specifications while using specification voltage is a very wise choice at this point (use enough voltage for the RAM to run its specified speeds). We probed actual VDimm levels with a DMM to ensure that BIOS set values are not adrift from user set BIOS values. We could not find any significant level of voltage droop/undervolting/overvolting under idle or load conditions.
Our recommendations in terms of RAM are that you choose a good kit that can run at least DDR2-1066 @ CAS5. (2GB or 4GB of OCZ CAS5 PC9200 RAM has proven very successful with the 913 BIOS.) This will push towards the best performance possible from this board. At this time the P35 Chipset seems to favor Micron D9GMH based modules over the highly regarded D9GKX bin. A reason for the preference of the lower bin is unknown at this time. Our D9GKX modules required higher levels of voltage than we were accustomed to providing them, and we were not able to match the D9GMH based module results in terms of speed, stability, or timings ranges. The advantage to the user is of course good performance for less money, as D9GKX based modules are typically more expensive than their lower binned counterparts.
Lower speed-binned RAM is usable by adjusting strap/divider/FSB combinations in BIOS, to stay within RAM capabilities at the expense of overall performance. Tests between FSB and chipset strap ratios show the performance penalty in real world applications and games benchmarks is very small.
Of paramount importance is a level of patience and perseverance. GTL tuning takes time but can be very rewarding in terms of performance advantages. Again, perseverance is the key! Now, this is what we did to help determine which settings to change.
- Run Prime95 in XP or Vista and note which cores fail. The reason the Prime95 Torture Test is recommended for this situation is that we can study which cores are failing the test consistently and then attempt to set the corresponding CPU core GTL values to improve failure time frames or eliminate failures altogether.
- Repeat the Prime95 Torture Test several times using the same settings to pick up patterns of time and core related failures (if you are experiencing them). At this point, as stated earlier, it is important not to be overzealous with tight RAM timing settings.
- If there is no pattern (i.e.; all cores fail at random), then consider tuning NBGTL by 1-2 digits in either direction, then monitor the effects again to look for changes from previous values. VCore, VNB and VDimm are all likely candidates if not within range.
- If GTL CORE 0/1 and GTL 2/3 values are close enough to optimum for your CPU, it is likely that tuning NBGTL will create a more predictable and consistent failure on one or two of the four cores. For most CPUs you will not have to stray too far from the NBGTL scale value to find this point, though we have heard of reports where some CPU/motherboards prefer the NBGTL at around a 66% mark of VTT.
- 1-2% variance between GTL setting adjustments sounds remarkably close between systems in theory
- Move the corresponding GTL scale for the failing core by adding or subtracting one digit from the recommended values in the VTT/GTL table, do not stray over 1-2 digits at a time, it is imperative to check for Prime95 failure times after EACH change in GTL value.
Remember up to the 913 BIOS the actual GTL core functions are mislabeled. The actual core each function relates to is shown below:
CPU GTL 1/3 REF Volt = GTL ref 0/1 (Cores 0 and 1)
CPU GTL 0/2 REF Volt = GTL ref 2/3 (Cores 2 and 3)
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Rocket321 - Tuesday, October 23, 2007 - link
I would like to see the overclocking results put into a graph or chart of some kind.I guess tweakers might like the screenshots as "proof" that the overclock ran, but personally I trust you and would rather just have one place to look rather than clicking to enlarge multiple screenshots sequentially.
It was a great review though, I look forward to the future tweaker guides & reviews.
Raja Gill - Wednesday, October 24, 2007 - link
There will be a more typical Anandtech look to future articles, with the DFI board revisited for a round up on a suite of benchmarks, this will be used to cross compare with other boards, clocked to equivalent with board maximums in the range and voltage. In terms of the screenshots, it is nice to have 1 persons trust, but there are many we have to please and not everyone is always as convinced..thanks for the suggestions..
Next up is the Asus Maximus Formula..
regards
Raja
Jodiuh - Thursday, October 25, 2007 - link
Specifically Windvd conversions from divx/xvid to DVD would be wonderful as I've found this app benefits from a solid OC.beoba - Friday, October 19, 2007 - link
It'd be great if this came with a glossary."Strap"?
retrospooty - Saturday, October 20, 2007 - link
strap is a term used for memory clocking. for example, at 266mhz bus, memory can be "strapped" to one of the following.266x(stap2)=533 or DDR 1066
266x(strap1.5)=400 or DDR 800
266x(strap1.25)=333 or DDR 666
If you are running at stock 266 there is no way to have DDR 950 because it has to be strapped to one of the above settings.
I use the 1/1 strap so my bus speed is 500x(strap1)=500 or DDR 1000, in most cases 1/1 is the most efficient, if you can utilize it with your particular hardware, do it.
Avalon - Thursday, October 18, 2007 - link
Unfortunately, DFI's asking price of admission continues to rise for each new board they release. I was mildly annoyed when they started selling boards for $200+ that had little to no tangible benefit over $100-$150 boards, but now they're at the $300 mark? No thanks.This board is for someone who likes to spend his time tweaking and not actually using his computer.
retrospooty - Saturday, October 20, 2007 - link
"This board is for someone who likes to spend his time tweaking and not actually using his computer."The article title is called "Tweakers Rejoice" after all. The idea is not to tweak forever . I did spend alot of time over the first few weeks, but now that its tweaked, I just use it as is.
Avalon - Sunday, October 21, 2007 - link
Yes, I am quite capable of reading the article title. My whole point is that you are working for diminishing returns that I feel could be better spent using your system. If you're doing it to set a record, fantastic. I support that.retrospooty - Sunday, October 21, 2007 - link
Understood... This is obviously not the motherboard for you. I personally love the BIOS options and CMOS reloaded functionality. That alone makes the extra cost well worth it to me. Asus BIOS just sucks, and I have had too many quality problems with them in the past, and Gigabyte just underperforms. I like to know I will not be held back by my motherboard for the next couple of CPU's I buy (will likely get a dual core Penryn on release for under $200, then a high end quad core Penryn a year or so later when it is under $200).I do see your point, but in spite of this article's stock speed comparison (totally pointless for a OC geared mobo), and similar results with one particular CPU, that looks as if it has an FSB limit equal on all 3 boards (meaning the CPU is holding it back) This board overclocks and performs better than any ASUS, or Gigabyte, or any other board out there. If AT tested the max FSB limits on a dozen or so CPU's, or if they had a "golden sample" that had a high FSB limit, you would see the difference. Also if they had time to test many diff RAM stocks and to tweak the memory settings you would also see the difference. Its a good article, but no reviewer has time to really dig into this mobo and all it has to offer. I do feel the article did a good job at explaining that.
JNo - Sunday, October 21, 2007 - link
"I like to know I will not be held back by my motherboard for the next couple of CPU's I buy"I don't know much about overclocking and I hold your views valid Retrospooty but surely this is still a lot of money that will still be needed to replaced in the short/medium-term if a) you want to start using DDR3 once prices come down b) if GPUs come out that take advantage of PCI-E 2 standard (as used on X38). So all that money is only paying for great OC'ing potential for *now* only... no?