System Builder Marathon: The $5,000 Extreme PC

Overclocking

CPU Overclocking

One might think that buying Intel’s best desktop processor would lead to a superior overclocking experience. After all, the Core i7 Extreme Edition 965 is supposed to be specifically selected for its tolerance to higher speeds and comes with an unlocked multiplier to further assist overclocking. We had high hopes, since our very first Core i7 retail sample, a lowly 920, was able to reach 4.0 GHz using air cooling and could maintain speeds of around 4.4 GHz on a water-cooled test bench.

Unfortunately, the i7 965 we received required more voltage to achieve similar overclocking-stability levels compared to the previously-tested i7 920. The higher voltage requirement made it produce more heat, which is, of course, an overclocker’s worst enemy. Even with our monster cooling system, the processor we used for today’s system couldn’t even reach 4,266 MHz at 1.45 V, and adding more voltage simply made more heat. Our i7 965 was actually worse than the i7 920 we’d tested before.

With 1.45 core V as the limit we’d chosen due to heat-and-longevity issues, we could easily reach 4.20 GHz but not much more. Additional testing proved that 1.3125 V was enough to keep us stable at this speed, and the lower voltage helped us to reduce the core temperature from approximately 83 degrees peak (Celsius at full CPU load) to around 79 degrees Celsius peak.

Our full-load CPU stability test uses four instances of the Prime95 Small FFTs torture test with affinity set to one instance per, and the temperature readings were taken using Realtemp at an ambient temperature of 26 degrees Celsius. These relatively harsh test conditions assured that the system would remain stable no matter what benchmarks we used.

DRAM Overclocking

A speed of 4,200 MHz is not a whole-number multiple of a standard 133.3 MHz base clock, so we increased this clock to 150 MHz. The resulting speed of each memory ratio changed and we selected DDR3-1800.

The higher DRAM clock required looser timings, so we switched from its DDR3-1600 rated 7-8-7-20 latencies to 8-9-8-20.

Graphics Overclocking

Nothing is more disappointing than overclocking a graphics card to a super-high speed, only to have it become unstable a few hours later. After trying dozens of settings, we finally settled on a GPU clock of 690 MHz, a shader engine clock of 1,520 MHz, and a memory data rate of GDDR3-2160. This probably isn’t the ultimate speed of these cards, but we couldn’t afford to waste any more time seeking diminutive gains.

Other Factors

One question that plagued our minds was whether the Aquagate Max pump, with its 3/8” coolant lines, was really capable of providing adequate flow to our high-capacity water block and radiator. After we had completed all tests, we pulled the platform and put it on our test bench, which uses a super-sized Swiftech MCP-655b water pump and ½” lines in addition to a three-fan radiator and Apogee GTZ water block identical to those of our $5,000 PC. Peak temperatures dropped by 3 degrees Celsius, allowing us to reach a stable 4,266 MHz clock speed at 1.450 V. These improvements are barely worth noting and were not used for today’s benchmarks.

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  • xx12amanxx
    Nice article!

    I wish i could own a rig like that,but it would be that or a 383 stroker for the F-body..lol I can dream cant I?
    1
  • Crashman
    xx12amanxxNice article!I wish i could own a rig like that,but it would be that or a 383 stroker for the F-body..lol I can dream cant I?


    383 strokers are for copycats. Basically, too many bad 400 blocks and people found a cheap way to re-use the cranks to make their 350's bigger. If you have THIS kind of money, you'd might as well go BIG BORE too. Maybe a bowtie block? At any rate, you'll win more races with a real 400 (or larger custom size) so long as the block is good.
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  • one-shot
    It is interesting to note on Page 14. On the Sandra XII Multimedia test the Core i7 965 @ 4.2GHz scored 486,971, while the i7 920 @ 4.0GHz scored 386,867. The difference was 200MHz and made such a large difference. Did the Intel SSDs influence such a large gain in performance or the DDR3 @ 1800MHz or perhaps a combination of both?
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  • Crashman
    45998 said:
    It is interesting to note on Page 14. On the Sandra XII Multimedia test the Core i7 965 @ 4.2GHz scored 486,971, while the i7 920 @ 4.0GHz scored 386,867. The difference was 200MHz and made such a large difference. Did the Intel SSDs influence such a large gain in performance or the DDR3 @ 1800MHz or perhaps a combination of both?


    The 965 has a higher-bandwidth QPI link, so it should be good for boosting at least a few synthetic scores.
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  • gim159
    BAH!! Why is it always Intel? Only Servers and people that wish they MAC should use Intel stuffs.. Who else is going to use all of it's features? Not gamers, that is for sure!! Like a gamer is going to spend the extra $$ for ECC memory and not spend it on more important stuff like a GC or a great board. That and an economy minded PC buyer will go AMD anytime, more bang for the buck...

    Also, Ati is better a better card, for linking I mean. The support may be crap, but it is usually worth it to get them! 4850 X2, Water cool one and watch the clock go through the roof!
    -24
  • xx12amanxx
    Intel is the fastest thats why...This is supposed to be an uber rig.

    Ya crashman thats the problem i dont have that kind of money..lol A fresh stock rebuild bolt on's and spray will have to hold me off until better times!
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  • gim159
    ¿ "Intel is the fastest" ? Amd 2.0 is a 4.0 in the intel world...
    -20
  • JeanLuc
    I would love to seen those Windows boot times with those RAID 0 Intel SDD's!
    6
  • gim159
    Yeah, Optimize the heck out of it and take all of the unnecessary stuff out.. Probably 4 sec boot, Awesome!
    -8
  • Crashman
    xx12amanxxIntel is the fastest thats why...This is supposed to be an uber rig.Ya crashman thats the problem i dont have that kind of money..lol A fresh stock rebuild bolt on's and spray will have to hold me off until better times!


    I spec'd out a friend's 406 C.I. mouse a few years ago and he got through under $4500 with aluminum heads and a roller cam!
    0
  • DjEaZy
    ... maybe build some AMD based systems too, to see, how they stack up against in price/performance... just for tha fun of it...
    2
  • _horse
    Great article!

    HOWEVER, Should have used an Antec1200 for that much coin on the case. I have one at home using water cooling and its so much easier than any other case I've used to date. Cheaper too, in this instance.
    3
  • Crashman
    _horseGreat article!HOWEVER, Should have used an Antec1200 for that much coin on the case. I have one at home using water cooling and its so much easier than any other case I've used to date. Cheaper too, in this instance.


    I've owned both, the Cooler Master is a nicer case. I mean, we're just throwing opinions around now, right?

    But the Cosmos S is far more portable, and it fits the big radiator perfectly. In fact, it's the only stock case to fit that radiator properly.
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  • LATTEH
    With a build like that you guys should have tryed to set Crysis with 16 AA!


    well it probably wont be playable but it would just be neat to see.
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  • _horse
    CrashmanI've owned both, the Cooler Master is a nicer case. I mean, we're just throwing opinions around now, right?But the Cosmos S is far more portable, and it fits the big radiator perfectly. In fact, it's the only stock case to fit that radiator properly.


    Thats true, but I didnt know we were going for portability here, especially with a liquid cooled system.
    1
  • rodney_ws
    There's no way that sound "card" is up to the level of a $5k rig.
    2
  • jcknouse
    Nice article.

    Question for the writing staff:

    Have you thought about taking all your review statistics, and assembling an "uber system" based on the best parts based on what you have found in your review tests?

    Just curious. I don't remember that ever having been done before here. And for $5,000, you surely could afford to throw together all of the top notch parts into a system for kind of a "what happens when you put all the best parts together" article.

    Now you guys have me itching to build a new system already...and I just built one back in September!! lol
    3
  • jcknouse
    That is a really good question too:

    With the width of the video cards, where would you plug in a soundcard? Does it use the 3rd PCI-E x16 slot?

    Just curious. I've always noticed how the ATX motherboard size standard hasn't shifted to grow with the growth of the size of components, such as video cards and component heatsinks.

    Limited room bites. lol
    1
  • cah027
    Why not 3 liquid cooled 285's. Maybe drop the Blueray and or go down to a 920 in the next one. Keep the SSD's.
    2
  • Crashman
    cah027Why not 3 liquid cooled 285's. Maybe drop the Blueray and or go down to a 920 in the next one. Keep the SSD's.SSD's are fast but the only benchmarks they matter in are the ones that don't count (synthetics)


    SSD's are fast but the only benchmarks they matter in are the ones that don't count (synthetics)
    1