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Power, Heat, And Efficiency

System Builder Marathon, March 2010: $3,000 Extreme PC
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Efficiency is a comparison of work completed to energy used. Overclocking forces higher power consumption, but can still result in improved efficiency whenever performance is increased by a greater amount than power consumption. We start our analysis by checking the amount of power used at the source.

At 160W, idle power consumption was already high before we overclocked. Pushing our processor 61% above stock had only a moderate impact on idle power use, yet its full-load power went up by 64%.

A drastic increase in full-load CPU temperature could have a greater effect on power consumption than the moderate increase in voltage, since semiconductors become less resistive as they heat up. Once again, we remind readers that this temperature was reached by running eight threads of Prime95 simultaneously over the period of several hours and that operational temperatures were much cooler.

The liquid-cooled graphics card amazingly operates at only 25.6 degrees Celsius over ambient at loads and settings, a full 66% lower than temperatures typically achieved with air-cooled cards. The drastic difference in CPU and GPU temperatures is probably due to a flow restriction at the GPU water block, where the CPU block relies on high volume, while the GPU block relies on high pressure. Were we to add a second graphics card, we’d probably connect its cooling lines parallel to the first card for increased flow through the water block and radiator.

Because some of our games showed CPU limits at default settings, a gaming performance increase of 31% at a 31% GPU overclock appears to have occurred by happenstance. In other words, the same GPU clock probably would have provided far lower performance gains had it not been accompanied by a significant CPU overclock, though many hours of additional testing would be required to show an exact numeric correlation.

A 40% increase in performance corresponds to a 53% increase in power consumption, dropping the overclocked configuration’s efficiency by 8%. While certainly no “green” PC, we’re sure there are many users who would gladly pay the higher power bill for this performance improvement.

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  • 25 Hide
    Crashman , March 16, 2010 6:42 AM
    zoemayneMore than 64GB is gonna be needed for multiple games and good apps... those ssd's can only handle 5 games max.


    You're repeatedly ignoring that it's 128GB, not 64GB, because the article repeatedly states that the drives are striped (Level 0) by the RAID controller. And there's a terabyte of added storage on top of that for stuff that isn't programs.
  • 13 Hide
    sid1712 , March 16, 2010 6:50 AM
    I couldn't have made it better. Amazing rig for a 3k budget.
  • 12 Hide
    Crashman , March 16, 2010 8:19 AM
    Quote:
    Nice as it is, my only complaint is that...
    Overclocked 5970 + i7 on a single 120.2?
    ARE YOU MAD!


    Well, the explanation is in the conclusion, the builder wanted redundant storage instead of the big radiator but chose neither, leaving enough room in the budget for anyone who wanted to copy the build to make their own upgrade choice.

    But what's not in the budget is that the water was never hot, it was barely warm. The problem with running the CPU at 100% load and the GPU at 100% load is that the water temperature went up by around 10 degrees...we're talking about going from the 30's to the 40's here at full load. The article points to the GPU cooler as a likely flow restriction so I have three solutions:

    Solution 1: Add 1/2" by 3/8" adapter T's and cool the chipset block, parallel to the GPU block. That would allow some of the water to bypass the GPU cooler, which is OK since the GPU was always cold. But 1/2" by 3/8" T's are hard to find outside of a hardware store, and Newegg certainly doesn't have them.

    Solution 2: Switch to a 3-fan radiator. A 4-fan unit won't fit nicely into that case, and making an ugly system wasn't considered a solution.

    Solution 3: Add a second liquid-cooled 5970 parallel to the first. Get twice the GPU power and completely unblock the lines in the process. The GPUs would run slightly hotter when each gets only half the water, but at least the CPU block's flow won't be restricted. And...since it's probably adding another 10 degrees to the coolant...stick the three-fan radiator in there as well. For FOUR grand you could have a KILLER system!

    OK, so solution 1 is the cheapest, but you have to admit solution 3 is tempting...
Other Comments
  • 25 Hide
    Crashman , March 16, 2010 6:42 AM
    zoemayneMore than 64GB is gonna be needed for multiple games and good apps... those ssd's can only handle 5 games max.


    You're repeatedly ignoring that it's 128GB, not 64GB, because the article repeatedly states that the drives are striped (Level 0) by the RAID controller. And there's a terabyte of added storage on top of that for stuff that isn't programs.
  • 13 Hide
    sid1712 , March 16, 2010 6:50 AM
    I couldn't have made it better. Amazing rig for a 3k budget.
  • 6 Hide
    Onyx2291 , March 16, 2010 7:04 AM
    Nice fail there Zoe.

    This thing is a beast.
  • 4 Hide
    anamaniac , March 16, 2010 7:14 AM
    Nice as it is, my only complaint is that...
    Overclocked 5970 + i7 on a single 120.2?
    ARE YOU MAD!
    Likely.

    Well, I personally would have dropped something else and gone for a 120.3 or 140.3 radiator. =D
    Hell, maybe even a 140.4 radiator, but then again, I like my system to run chilly and silent. It's also be very difficult to mount a 140.4 I assume. Maybe I could jack a radiator form work, I think it's about 1 metre by 3 metres by half a metre. Granted, it's for industrial use, but just for one day, please boss please?

    Good results on the i7 though. Decently low voltage and still managed to reach 4.3GHz. My i7 is a lemon. It makes me sad. =(
    Also an impressive overclock for a 5970.

    At this kind of power, you should be testing multi monitor resolutions. I have a 5770 and I run 7 megapixels, you use a 5970 and only run 4 megapixels.

    Looking forward tho the $1,500 build. See how my build compares to one six months older on a similar budget (and cry).
  • 12 Hide
    Crashman , March 16, 2010 8:19 AM
    Quote:
    Nice as it is, my only complaint is that...
    Overclocked 5970 + i7 on a single 120.2?
    ARE YOU MAD!


    Well, the explanation is in the conclusion, the builder wanted redundant storage instead of the big radiator but chose neither, leaving enough room in the budget for anyone who wanted to copy the build to make their own upgrade choice.

    But what's not in the budget is that the water was never hot, it was barely warm. The problem with running the CPU at 100% load and the GPU at 100% load is that the water temperature went up by around 10 degrees...we're talking about going from the 30's to the 40's here at full load. The article points to the GPU cooler as a likely flow restriction so I have three solutions:

    Solution 1: Add 1/2" by 3/8" adapter T's and cool the chipset block, parallel to the GPU block. That would allow some of the water to bypass the GPU cooler, which is OK since the GPU was always cold. But 1/2" by 3/8" T's are hard to find outside of a hardware store, and Newegg certainly doesn't have them.

    Solution 2: Switch to a 3-fan radiator. A 4-fan unit won't fit nicely into that case, and making an ugly system wasn't considered a solution.

    Solution 3: Add a second liquid-cooled 5970 parallel to the first. Get twice the GPU power and completely unblock the lines in the process. The GPUs would run slightly hotter when each gets only half the water, but at least the CPU block's flow won't be restricted. And...since it's probably adding another 10 degrees to the coolant...stick the three-fan radiator in there as well. For FOUR grand you could have a KILLER system!

    OK, so solution 1 is the cheapest, but you have to admit solution 3 is tempting...
  • 0 Hide
    Sihastru , March 16, 2010 8:50 AM
    I kinda like it. Dramatic power increase for the overclocked components. But also dramatic performance increase.

    Another solution to the constricted water flow would be to change the block on the 5970.

    This build gets one and a half thumbs up from me, not that anyone cares...
  • 8 Hide
    tecmo34 , March 16, 2010 9:23 AM
    Only changes I would've recommended is...

    Storage HDD: Samsung Spinpoint F3 1TB - $90
    RAM: G.SKILL PI Series 6GB (3 x 2GB) 240-Pin DDR3 SDRAM DDR3 1600 - $180

    Those would still get you in at $3,000 provide an increase in performance with the Cas7 DDR3 1600 RAM and a faster hard drive (well, if you really need faster with two SSD in RAID0 :D  ).
  • 4 Hide
    JeanLuc , March 16, 2010 9:56 AM
    I don't know why someone marked down tecmo34 comments, if you going to mark down a comment at least have the good curtsey and explain why you disagree (unless it's blindingly obvious like the post left by tacoslave).

    I too would have used the Samsung Spinpoint F3 1Tb it's been reviewed countless times and benchmarked against all the competition and wins every time.
  • 2 Hide
    cscott_it , March 16, 2010 10:19 AM
    So....You guys planning on giving this beauty away?

    Seriously though, great review. It makes me seriously consider switching to water.
  • -2 Hide
    JohnnyLucky , March 16, 2010 11:34 AM
    Will the prices continue to rise, will they level off, or will they decrease this Summer?
  • -6 Hide
    teslaxero , March 16, 2010 12:38 PM
    Here is what I would like to see...

    Swap the case for a goliath sized Antec 1200, add another 5970 and a seperate water cooler 120.3 for the pair. Now the CPU and GPU's have a water supply independant from each other. Overclock that monster!
  • 2 Hide
    jeverson , March 16, 2010 12:41 PM
    The only thing I would have changed would be the case to a COOLER MASTER CM690 II Advanced. It already includes a mount for 2 SSD drives and can accommodate 2 radiators internally. Aside from that, very nice build and I look forward to a chance to win it... ;) 
  • -1 Hide
    banthracis , March 16, 2010 12:52 PM
    teslaxeroHere is what I would like to see...Swap the case for a goliath sized Antec 1200, add another 5970 and a seperate water cooler 120.3 for the pair. Now the CPU and GPU's have a water supply independant from each other. Overclock that monster!


    There is a $3000 budget limit you know. Curious as to why you guys didn't go with the Vertex LE for the SSD. Granted it's only 100gb and was $400, but it's a very large boost in performance, putting even the Intel X25 G2 drives to shame.
  • 0 Hide
    blackened144 , March 16, 2010 1:31 PM
    banthracisThere is a $3000 budget limit you know. Curious as to why you guys didn't go with the Vertex LE for the SSD. Granted it's only 100gb and was $400, but it's a very large boost in performance, putting even the Intel X25 G2 drives to shame.

    Those SandForce powered drives have amazing performence.. But that drive alone is nothing compared to the 64bg drives in raid0.. Plus you get an extra 28gb with the 2x64gb setup..
  • 0 Hide
    Anonymous , March 16, 2010 1:52 PM
    What's the boot time???
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