ATI 4850 benchmark

Discussion in 'Graphics Cards & Displays' started by Chai, Jun 19, 2008.

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  1. Chai

    Chai Administrator Staff Member

    Since you have a lot of trouble trying to understand me, I make it really simple for you. As long as it's stable, you shouldn't need to care about temperature.

    Why am I? Simple. That's because I always run my CPU way above the recommended clockspeed. Hence the rated temperature tolerance do not apply to me anymore.
     
  2. Mac Daddy

    Mac Daddy Pickin' Da Gitfiddle

    That is exactly why I mentioned it and why bipolar junctions aren't used in modern dies. A Darlington pair also has a high input impedance but since it is a bipolar device it doesn't have a negative temperature co-efficient. This means that when the junction temperature increases the impedance also decreases and leaves the junction up for a condition known as thermal runaway.

    What books do I need to hit again?
     
  3. Mac Daddy

    Mac Daddy Pickin' Da Gitfiddle

    You seem to miss the whole point the testing procedure used for temperatures on that article are inaccurate you more or less said so yourself. What was posted there was raw data which Delta T isn't. Delta T is a analysis of raw data not collection of the data itself. I will be getting into more of that in my next review.

    A question ... when you overclock your video card to high and experience artifacts what physical property ultimately causes them?
     
  4. Mac Daddy

    Mac Daddy Pickin' Da Gitfiddle

    I understand your point and that's why I use coolers as well but I think your missing my point. Frequency also causes the junctions to heat as well as voltage and current. My point is simply that no semiconductor will operate efficiently at higher than its rated temp. As long as proper cooling is used we can regulate this somewhat while overclocking and overvolting.. Are we just saying the same thing? :think:
     
  5. Max_87

    Max_87 huehuehue

    Stop twisting what I'm saying. You were the one who keep questioning why 4870 has lower load temperature than 4850, and I gave you the most possible answer.

    Enough is enough. All you do is evading your own mistakes and twisting around what we said. Time for the LULZ.

    Ok, you were questioning WHY THE HELL 4870 has lower temp under load. The most possible answer? The cooler on 4870 is made to keep the temperature below 83C, but the 4850's cooler is not. You did not read the article properly yourself! but that's fine.

    But then you reply:

    Oh, so NOW you realized that you did not read the article properly, you did an AWESOME high speed 90 degree cornering said that the article has inaccurate results because it's not Delta T blabla. If you agreed with what we said about Delta T, then you should know that the temperatures are meaningless and shouldn't be taken too seriously. RIGHT?

    and yet WHY, WHY were you STILL questioning 4870 has lower load temps than 4850? Who was the one that missed the point?

    I take the results as a grain of salt because the readings is not in delta T. You were the one who take the "temperatures" too seriously.

    PS. Oh and what about the MOSFET not being able to operate efficiently at 80C? LMAO!
     

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    Last edited: Aug 7, 2008
  6. Max_87

    Max_87 huehuehue

    I thought you and PsYkHoTiK were supposed to be talking about MOSFETs?

    You were the one who said MOSFET has negative temperature co-efficient.
    and then you suddenly said:
    Aren't you contradicting yourself? :haha:

    then you went on and said:
    So this is why you were contradicting yourself? That's really awesome :mrgreen:


    :haha:
     
  7. PsYkHoTiK

    PsYkHoTiK Admin nerd

    lol.

    He can create a thread on MOSFETs if he wants (I really have no intrest in partaking a discussion that goes loopy).

    Let's stick on topic on the cards. :p

    I personally, am considering this card (and its ~200w idling glory). It should go well with my block and various chipsinks to cool everything down. :p
     
  8. Max_87

    Max_87 huehuehue

    Yup :mrgreen: If you are not happy with the operating temperature, just upgrade the cooling! Otherwise it runs just fine with the stock cooler as it is designed to keep the operating temperature below the threshold. Unless you are overclocking it of course.
     
  9. Mac Daddy

    Mac Daddy Pickin' Da Gitfiddle

    Well lets make one last post on this thread for all our up and coming Electronics experts :mrgreen:

    Bipolar semiconductors have a positive temperature co-efficient while MOSFET's have a negative temperature co-efficient. So in essence by forcing a "FET" based semiconductor to higher temperatures you are basically going against its basic properties in Physics. So it will never be completely stable under those conditions.

    Do we understand semiconductors in general now?

    Max on artifacts it is HEAT as that is the basis for 99.9 percent of semiconductor failures no matter what parameter caused it. Try googling that :wave:

    Well besides petty insults and people who need real life experience on more than a few issues lets get back on topic. I do believe Goldfries picked up a 4850 lets see if he records temperatures properly using manual fan settings ;)
     
  10. Chai

    Chai Administrator Staff Member

    Yes, correct. But do you know what is the max rated temperature in the first place??? The answer is no! Even I do not know.

    But what I do know is back on 6800 Ultra, on the Geforce control panel, the Max Temp before throttling was about 100+C. If they allow the card to run up to 100+C, it means the max rated temp is even higher than that. I'm not saying that ATI will have the same max operating temperature, but I wouldn't be surprised if it's similar.
     
  11. Yukirin

    Yukirin Newbie

  12. Max_87

    Max_87 huehuehue

    You are still saying that? We might not know about electronics as much as you do, but...

    MOSFETs Basics

    International Rectifier - HEXFET Power MOSFET Product Information

    Hot-swap MOSFET reliability - 4/1/2004 - EDN

    LOL? empire23, we could use some help here :mrgreen: Maybe empire23 can explain why all the google results are saying the opposite

    Yeah, there's no need to mention that over and over again. All of us here know that when the temperature go out of manufacturer's specification, the cards will produce artifacts.

    I wonder who was the one that started making insults first :lol: Sometimes these people really amuses me when they act all high and mighty.
     
    Last edited: Aug 7, 2008
  13. empire23

    empire23 BRB. Attacking Russia

    I'm not going to say who's right and who's wrong, but i'll try to clear the air regarding MOSFET topology and ideals. The are a few misconceptions flying around so i'll correct them.

    1. There's no set definition for negative and positive thermal coefficient. The words themselves don't matter unless they're put in a useful context. Engineers throw around these phrases with charts included, so one has to switch their definition to meet the situation. It's just one of those phrases that changes meaning depending on the person using it.

    AMB.org run by Ti-Kan lists it as negative, IOR as positive, Diodes Inc as negative and so on. My advice is to see what the words reflect above all. EE people aren't into semantics, that's why we keep using words depending on like and need.

    Even my Modern Electronic Communications textbook by Gary M Miller and Beasly has alot of definitions that my cranky old lecturer Bruce Varnes defines as ;

    a) Hogwash
    b) Pure Incompetence
    c) Miller was educated with a different system than what the world uses.


    2. BJTs are the ones that suffer from thermal runaway, as current to current devices as they pass current, it heats the BJT up, and thus the BJT passes even more current which leads to even more heating. This is thermal runaway in the purest sense.

    3. MOSFET are the opposite, as voltage to current devices, they take up extremely low levels of gate drive current, in the nano amp region. As MOSFET heat up due to current travelling via the drain and source, their on resistance increases instead, limiting current flow. This acts as a varistor, and like a varistor, it WILL heat up, but it WILL NOT pass more current.

    4. Regarding Clocking FETs higher and higher, realize why a boost of say (analogy) 10 percent voltage will net you 10 percent clock gain and as you go higher to 20 percent, you'll only get a say 15 percent improvement instead of 20? It's because MOSFET don't scale linearly after they exceed their efficient operating zones. You get a compressive function of gain versus voltage. There's only so many volts you can push through a FET till that poor depletion layer breaks from the voltage on the gate.

    5. Stability in a practical sense is defined by the ability of a device to deliver results within it's specified boundaries. Stability also can be defined as a suitable MTBF. Which we don't know. Of course, stable short term doesn't mean much, as we all know thermal stress can not only stress a part electrically, but also physically, flexing pads, joint stress and other problems manifest themselves in the long term.

    An EE/CE/SE's job is to make sure that the device is long in the bin before these effects start to show. Basically, when dealing with high power devices, actually, most devices, heat is the biggest issue of design.

    6. Different Processes give different temperature tolerance, different designs also give different power outputs, complimentary logic cells are heat blasters IIRC. Generally we're taught here to make sure MOSFET don't hit the 70+ region for stability, IIRC an LYN forumer Sniper on the Roof who's an industry insider says that too. BUT one can get away with going higher by generally

    - Giving long term reliability the ass end.

    MOSFETs can run for a gajillion years at lower temps without the threat of high voltage, but people replace their GCs in probably 3 years, so, one makes a compormise in the search for high clock speed and ass beating performance level.

    - "Assume" perfect operating spec.

    A favourite excuse everyone in this business plays, one assumes everyone lives in the Siberian wastes and then figures that people in hot countries are too poor to buy their stuff. It depends from manufacturer to manufacturer, and it depends on their desperation lol.

    ATi during their X1800 days, knowing that Nvidia had em in a pinch tended to stretch their defition of "reliable operating region", Nvidia did the same with their 5XXX series of cards.

    Just givin my 2 cents, not supporting anyone. Just here to tell ye what i know. ;)
     
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  14. PsYkHoTiK

    PsYkHoTiK Admin nerd

    Very very good post Empire23... +rep :thumb:

    Very good points on the 3 years, MTBF and operating temps and how it affects efficiency. :thumb:

    A really good 'bigger' picture post which coincides with the points Chai and max brought up. :clap:
     
  15. empire23

    empire23 BRB. Attacking Russia

    Haha, this thread has reminded me that i want to build a new rig for all my photo editing, gaming and review needs. Going to have stuff shipping to me and hopefully i can get enough work done to sponsor Twin 4870s for this new rig.

    Got the 8gb of memory required, got the PSU....now for the rest.
     
  16. Unixlord

    Unixlord Newbie

    A yorkfield and an X48 motherboard, a well ventilated full tower case.
     
  17. Lacus

    Lacus Newbie

    Twin 4870 O_O..why don't just get twin 4870X2 :D
     
  18. Chai

    Chai Administrator Staff Member

    Maybe he meant twin 4870X2 LOL
     
  19. empire23

    empire23 BRB. Attacking Russia

    Not much money for now, just a twin 4870 seems good. Just wanted to jumpstart my old reviews ASAP and i need a rig to do it.

    Not to mention slogging through labview charts, tekscope bmps and other shit takes a lot of effort on this lappie.
     
  20. miahman

    miahman Newbie

    i was searching for crossfire compatible GPU. and i came across a graphic card which is DDR3 and DDR5.

    i know DDR3 can be used with DDR3 mobo. but in order to use its DDR5 speed do we need to wait for new DDR5 mobo's or is there another way to use it?
     
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