Reboot, probably the PSU but need to know

By Magwill
Mar 19, 2005
  1. ASUS A7V333
    AMD 2100+ running at 1700 Mhz (original fan)
    ASUS v9999 GeForce 6800
    512 DDR

    Ok so I used to have a ASUS v8420S GeForce Ti4200 but I had overheating problems. Smart as I was I let the computer suffer with an open case for over a year. Smart as I was I didn't noticed that the fan was broken until that year had passed by. So I couple of days ago the card died of course. I took action and bought the new video card listed above and a case-fan (Papst 80x80). I also did a thoroughly cleaning of dust (even opened the PSU and cleaned it). I thought that my problems would finally be solved but when I played the new Brothers in Arms yesterday for some hours I got a bluescreen. So I restarted, and another bluescreen. After the 4 different bluescreens I recognized the pattern of an overheated AMD CPU. So I went into BIOS and checked, and damn it was 78 Celcius!! The CPU Fan was only going for 2000 as well! In those temperature they should go at max (arond 5000 RPM in this case).

    I started to monitor my hardware with ASUS Probe and played for awhile later when the CPU had cooled down. After 30 minutes the computer rebooted telling me no keyboard was detected. I pressed the reset button and I it worked fine this time. Later when checking the loggings of Probe, the CPU temperature was steady at 58 celsius and MB temp was at 44 at the reboot time. The disturbing thing I noticed was that at once I started playing the game my 3,3 V started sinking. At the time the computer rebooted it was as low as 2,5.

    I'm not any hardcore PC modder so I have no idea what this really means. My guess is that since the Video Card uses Power directly from the PSU it may consume too much and then all hell breaks loose when other components aren't getting enough power. My PSU is probably really lousy since it is only a cheap 300W.

    So the questions:
    What is the 3,3 V responsible for? What parts use it?
    Is a new PSU the solution?

    Thanks in advance
  2. fishhookz

    fishhookz TS Rookie Posts: 79

    I never heard of anyone with 300W PSU running a stable gaming rig with 6800.

    As for the fluctuating voltage, I think we can attribute it to the 6800 drawing more power in games. I assume the 3.3V is +3.3V of the PSU listed on the front page of ASUS Probe. Typically, anything beyond a 5% drop or raise is a bad thing.

    I can't guarantee, but I'd say PSU. 480W or more. Brand name like Antec, TT, etc.
  3. Magwill

    Magwill TS Rookie Topic Starter

    Thanks for the answer, I needed another opinion on this matter. Since I'm a student and low on cash I thought of Aspire ATX-AS500W 12V
    Aluminum See-Through Power Supply instead of those brands you mentioned. Do you think it would be sufficent?
  4. fishhookz

    fishhookz TS Rookie Posts: 79

    I don't know about that brand. What you should look for in a PSU is 15A or more on the +12V rail and 20A or more on the +3.3V and +5V. This should be on their website.
  5. nein

    nein Banned Posts: 109

    Logic voltage for nearly everything in your system.
    Go ahead and get a new PSU.
    Its a good thing you had noticed, most people can't including "experts". They always gave ignorant dumb advices like getting PSUs with lots and lots of fictional 12V power.

    Remember this - If your 3.3V and 5V combined power rating is really wimpy. When power demands went up for any others such as 12V, its your 3.3V and 5V logic voltages which will drop-out causing reboots. All power taps shared the same source origin.

    When 3.3V and 5V being sufficient while not so for 12V, your system would stutter or hangs instead of rebooting.
  6. Magwill

    Magwill TS Rookie Topic Starter

    Ok this one has
    +3,3 28A
    +5 30A
    +12 34A

    I'll think I go for it then
  7. Magwill

    Magwill TS Rookie Topic Starter

    Ok thanks for the information :) I think I'll go for this PSU then since apparently it's +3,3 and +5 ampere together is quite good. Thanks all.
  8. Magwill

    Magwill TS Rookie Topic Starter

    Well just installed my new Aspire 500W PSU and tried Brothers in arms out, flawless :) No instability what so ever! The only thing I have to ask now is that the 12V rail is at 13 almost all the time, I know this is over the 5% limit and just a bit below the 10%, what problems could a high 12V bring?

    PS. Might add that I read some articles regarding the GeForce 6800 series and their power consumption, and they recommend that you have a free Molex cable to the graphics card (no other devices connected to the same power-cable), so I did this as well.

    Edit: Before I changed PSU my temperatures in idle were
    CPU: 55
    MB: 44

    With the new PSU they've gone to:
    CPU =45

    Which is nice :)

    And thanks everyone!
  9. fishhookz

    fishhookz TS Rookie Posts: 79


    "the 12V rail is at 13 almost all the time" - I hate to be the bearer of bad news, but it sounds like it's the PSU doing it. Hence, I'd pick a brand name.

    Since you're having no probs other than the 12V rail, you're ok. I guess your new PSU has 2 fans with one pulling hot air near the CPU.
  10. nein

    nein Banned Posts: 109

    Mostly it meant nothing technically relevant to worry about. 12v hardware had been around nearly forever, they normally operated within the range of valid lead-acid batttery output - 10.8V to 13.2V, a fully charged lead-acid battery stabilized out at 11.8V nominal. If you bought any common 12V hardware which could not do so, get rid of them, they were designed or built by retards.

    The above is the norm for most all 12V voltage regulator devices for years and years but few exceptions.

    What you're looking for is deviation from nominal voltage to determine the quality, if your 13V output essentially never deviate from 13V or little if any deviance detected at all under all loading condition then it is a good 12V supply.

    The larger the deviance percentage from nominal under all loading condition the worst the 12V supply. A power supply with "wandering voltage level" from nominal is a bad power supply, a good perfect one simply doesn't deviate fom nominal voltage under any load condition, up or down.
  11. Magwill

    Magwill TS Rookie Topic Starter

    Thanks for the info both of you, the 12V rail is very stable so seems it is good then!
  12. justin092300

    justin092300 TS Rookie

    I've had a very similar problem with my computer. It reboots at random times but it almost always reboots when playing BF2 or CS:Source. I've noticed it happens almost always after it has been running for a while and I go to start one of those games. At first I had a problem with it rebooting all the time until I downcloked to RAM to 166Mhz (333). Nothing is overheating so nothing there. I am a novice when it comes to voltages though. I went with this PSU because of the 6800GT needing more power. When I look at ASUS PC Probe while the PC is idle the voltages read: 12.5; 4.865; 3.296; 1.68. I recorded the voltages and started playing BF2; it rebooted when I went to quit the game the last voltages shown on the history were: 12.736; 4.73; 3.264; 1.696. ANYONE GOT ANYTHING?

    MB: Asus A7N8X-X
    CPU: Athlon XP 3200
    RAM: 1GB Kingston Value RAM PC 3200 (downclocked to 333Mhz due to instability with nForce 2 chip
    VGA: XFX GeForce 6800 GT (AGP)
    PSU: Antec Smart power 500
    HDD:WD1200JB; 120GB
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