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Thread: Proper PSU for two R9 295x2 in crossfire

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    Quote Originally Posted by jonnyGURU View Post
    So.. if your OCP is 30A and current exceeds 30A, the PSU shuts off.

    If you have no OCP, whatever the PSU can provide to the +12V rail TOTAL will attempt to go down the wire if there's a short. This amount of current, say 125A in the case of an AX1500i, is WAY MORE than any PSU wire, connector pin, etc. can handle.

    OCP can be important. It's like airbags in a car. You hope to never need them, but you're glad it's there when you DO need them. Just last week, we had a customer with a CX750M. A PSU w/o OCP. His optical drive died on him. Something inside went >>ZAP<< and shorted the +12V. But because the CX750 has 62A available on the +12V, the load just kept increasing and increasing until the connector and wire insulation on the lead going to the optical drive got so hot that they melted. Not pretty. A 1 in 100,000 incident? Probably. But still.... not pretty.
    Well, my guess is, if i want to use the setup i currently have, i need to buy a fire extinguisher, eh?
    I don't know if i've mentioned it or not, but i have my PC connected to the wall somehow like this: 220V outlet -> surge protector (i am currently using this: APC P1-RS, but i also have brand new ZIS Pilot Single) -> voltage regulator (SVEN AVR-2000 LCD) -> PC. Do i need to add a PSU into this combination or something else?
    Last edited by yifeng3007; 09-14-2014 at 02:46 PM.

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    Quote Originally Posted by CM Phaedrus View Post
    OCP is kind of like the circuit breakers in your house. Each circuit in your house gets its own breaker; likewise each cable or group of cables leaving a multi-rail PSU has an OCP "breaker", where if there's a short circuit or an overload condition that could damage the PSU, the PSU will shut off to protect itself.
    Wow, that's a great analogy, i think i get it, thank you for the explanation!

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    So, since it's been a long time i've written something in here i want to apologize for any inconveniences: my school started a week ago, so i was a little busy. But that's an offtopic.

    A couple of weeks ago i got my new Corsair AX1500i and i immediately installed it.

    And since then i continue to run into problems. So for a week or so, when i play BF4 on ultra in 4K scaling, my PC will shutdown after 3-5 mins of gameplay. Also, when i just browse internet and watch some flash videos my PC BSOD's with an error 0xa0000001. I've read somewhere, that it might be the problem with insufficient PSU power delivery to the cards.

    So what i've done is, i lowered OCP of unused rails to 20A and left 30A cap on the rails that are used by the video cards untouched. It fixed the issue of shutdowns and BSOD's.
    I thought so, until this issue happened to me 15 minutes ago (BF4 on ultra settings, 4K scaling -> 2 min gameplay -> shutdown with no error) and now i really don't understand what should i do, or what seems to be the problem.

    P.S.: my MoBo has an individual sata power connector for systems, that use more, than 2 PCIe slots, and it is connected to the PSU.

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    LOL!

    First: If you read somewhere that insufficient power to the graphics cards causes BSODs.... read a different website.

    And, as for the OCP... think about what you're doing....

    When you >>LOWER<< OCP, you're actually lowering the trip point that the PSU trips off at. So why do you think lowering the OCP prevented the shutdowns?

    Remember what Phaedrus said.... OCP is like circuit breakers. So what you did was like this: "I have 20A breakers in my house. My TV kept shutting off. I took out the 20A breakers and installed 10A breakers and now the TV works fine." Does that make sense to you? Because it shouldn't.

    So, if you actually work off the "BSODs mean not enough power" train of thought... you just debunked that by LIMITING the amount of power to other parts of the board (since it's the OCP on the connectors NOT going to the graphics cards) and the BSOD's went away. Doesn't make much sense, does it? Unless you're thinking that by limiting the OCP to other parts of the board, you're increasing the power available to other parts. I hope that's not what you think because that would be mind blowingly (no offense, because I know you're new at all of this) ignorant.

    Was this the first time you changed anything under the power tab in Link... or was it the first time you decided to use Link?

    Of course, all of this playing with Link and OCP, etc. could be completely coincidental since the problem only went away for a while and then happened again playing BF4.

    Have you tried the PC with one graphics card at a time? And if so, what happens?

    The tried and true way to troubleshoot is to NOT throw all your hardware together and go "hmm.... now what?" It's to slowly and methodically look at each part one at a time, and since you have the luxury of two graphics cards, you have the luxury of trying them one at a time to see if one of the cards is bad.

    If you don't feel like doing that quite yet, we can still play the "not enough power" angle, but you're going to need to use Link.

    Remember: Link doesn't only allow you control of the PSU. It allows you to monitor it as well. Turn on logging and have it monitor the current on ALL of the modular connectors. That includes the CPU. Even if the PC shuts down, I believe it will still write the log file. Post the results. Let's see how high that power draw actually gets. If it's nowhere near 20A or whatever you have the OCP set to in Link, then that's certainly not the problem.

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    Quote Originally Posted by jonnyGURU View Post
    When you >>LOWER<< OCP, you're actually lowering the trip point that the PSU trips off at. So why do you think lowering the OCP prevented the shutdowns?

    So, if you actually work off the "BSODs mean not enough power" train of thought... you just debunked that by LIMITING the amount of power to other parts of the board (since it's the OCP on the connectors NOT going to the graphics cards) and the BSOD's went away. Doesn't make much sense, does it? Unless you're thinking that by limiting the OCP to other parts of the board, you're increasing the power available to other parts. I hope that's not what you think because that would be mind blowingly (no offense, because I know you're new at all of this) ignorant.
    So, actually, this - Unless you're thinking that by limiting the OCP to other parts of the board, you're increasing the power available to other parts., is exatcly what i thought

    Please, don't think i might be offended or anything! I've come to Your forum, because i know, that this is possibly the only place i can get constructive criticism and best advises, so i am REALLY thankful to You, that You tell me where i am wrong!

    Quote Originally Posted by jonnyGURU View Post
    Was this the first time you changed anything under the power tab in Link... or was it the first time you decided to use Link?
    Well, i started to use Link, as soon as i got Corsair H80i cooler and AX1500i PSU, but, yeah, it was the first time i tried to change something under the power tab.

    Quote Originally Posted by jonnyGURU View Post
    Of course, all of this playing with Link and OCP, etc. could be completely coincidental since the problem only went away for a while and then happened again playing BF4.
    I am very sorry, i forgot to mention, that first, when i was having sudden PC shutdowns, i didn't pay much attention to it and just turned on the PC and continued playing. Everything was working fine, after this self-shutdown, until next reboot/sleep/turn off.

    After a couple of days my system started to act really weird in BF4: it had awful microstuttering, almost making the game unplayable, but when i turned on V-Sync in-game everything started to work very smooth (V-Sync off - barely 30 fps, V-Sync on - 55-52 fps), although i still had this freezes. So i decided to completely reinstall the graphics driver and after i've done that, all the freezes are gone, everything was all butter-smooth, but this self-shutdown occurred all of a sudden :C

    Quote Originally Posted by jonnyGURU View Post
    Have you tried the PC with one graphics card at a time? And if so, what happens?
    Yes, i have tried both cards individually, and they all work absolutely the same. I also tested them on Lepa P1700M and i had no issues whatsoever.

    Quote Originally Posted by jonnyGURU View Post
    The tried and true way to troubleshoot is to NOT throw all your hardware together and go "hmm.... now what?" It's to slowly and methodically look at each part one at a time, and since you have the luxury of two graphics cards, you have the luxury of trying them one at a time to see if one of the cards is bad.
    I'll do this again either tomorrow or on wednesday, when i'll have more spare time after university.

    Quote Originally Posted by jonnyGURU View Post
    If you don't feel like doing that quite yet, we can still play the "not enough power" angle, but you're going to need to use Link.

    Remember: Link doesn't only allow you control of the PSU. It allows you to monitor it as well. Turn on logging and have it monitor the current on ALL of the modular connectors. That includes the CPU. Even if the PC shuts down, I believe it will still write the log file. Post the results. Let's see how high that power draw actually gets. If it's nowhere near 20A or whatever you have the OCP set to in Link, then that's certainly not the problem.
    I'll do anything, just to solve this problem
    So, i guees i'll just revert all the power settings in Link to original one's and start logging. After that i'll do what is shown in this video here: http://www.youtube.com/watch?v=LPZe244Ufv0 at 8:20. In there you can see, that his OCP is set to 20A, that's where i actually took the idea to lower the OCP...
    Motherboard - GIGABYTE GA-Z97X-GAMING G1 WIFI-BK, CPU - Intel Core i7-4790K (@ stock), Cooler - Corsair H80i, RAM - 4x8GB Corsair Vengeance LP, SSD - Samsung 840 Evo 500GB, HDD - WD Black 1TB, Video Cards - Sapphire Radeon R9 295x2 and PowerColor Radeon R9 295x2 in QuadFire, PSU - Corsair AX1500i, Case - Corsair Obsidian 900D

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    Ahh!!!! So you tried the Lepa PSU and everything works fine?

    Ok... Somehow I missed that.

    Go into Link, check all of the OCP boxes and crank them up to 40A. Go do some normal web stuff... Just so we're 100% sure that the Link settings are writing to the PSU's MCU.

    After some time, go back into Link and uncheck all of the OCP boxes. Wait a couple minutes and then try again.

    Also, make sure you don't discontinue power to the PSU by turning it off via a power strip, etc. Because there's two very annoying bugs with Link:

    1. When you unplug an AXi PSU, all of the settings revert back to default.

    2. The current version of Link doesn't poll the PSU for settings. By default it says that OCP is disabled, which isn't actually the case. That will hopefully get fixed in future versions.

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    Quote Originally Posted by jonnyGURU View Post
    Ahh!!!! So you tried the Lepa PSU and everything works fine?

    Ok... Somehow I missed that.

    Go into Link, check all of the OCP boxes and crank them up to 40A. Go do some normal web stuff... Just so we're 100% sure that the Link settings are writing to the PSU's MCU.

    After some time, go back into Link and uncheck all of the OCP boxes. Wait a couple minutes and then try again.

    Also, make sure you don't discontinue power to the PSU by turning it off via a power strip, etc. Because there's two very annoying bugs with Link:

    1. When you unplug an AXi PSU, all of the settings revert back to default.

    2. The current version of Link doesn't poll the PSU for settings. By default it says that OCP is disabled, which isn't actually the case. That will hopefully get fixed in future versions.
    It happened to me again, when i cranked my upscale settings to 200% on 1920x1080 in BF4 (so the resolution would be 4K). At that time it crashed when i had all OCP boxes checked at 30A.
    Then, after the PC restart, i did as You said: cranked all the OCP to 40A, entered the game and the PC immediately crashed.

    I have a log file of that, but it's too huge D: Do you want me to send last seconds of it or everything?

    Update: I've found this VERY interesting article, but i would really love to hear Your opinion on it, before i do something. Can You please check it out? http://www.corsair.com/en-us/blog/20...on-the-ax1500i
    Last edited by yifeng3007; 09-16-2014 at 05:50 AM.
    Motherboard - GIGABYTE GA-Z97X-GAMING G1 WIFI-BK, CPU - Intel Core i7-4790K (@ stock), Cooler - Corsair H80i, RAM - 4x8GB Corsair Vengeance LP, SSD - Samsung 840 Evo 500GB, HDD - WD Black 1TB, Video Cards - Sapphire Radeon R9 295x2 and PowerColor Radeon R9 295x2 in QuadFire, PSU - Corsair AX1500i, Case - Corsair Obsidian 900D

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    That is his opinion. He wrote the article.

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    http://www.tomshardware.de/leistungs...te-241622.html

    Very interesting article, but not available in English (yet).

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