Did I hit my GPU limit? Or is my PSU too weak?

[tuesday0180]

I have EVGA GTX 470. I have clocked it to 800/1600/1950 with 1.087volts. I use it with the fan 100% and it has never crashed in 3dmark or battlefield 2 game play.


I tried upping it a bit more, but it would crash immediately. Does this mean I have hit my limit? Or is my weak power supply not giving enough power?

It says i need a minimum of 38amps for this gtx470.

My power supply has exactly 38amps. It is thermaltake purepower 600watt with 19amps per 12rail. Has two 12rails.


When it crashes I have to hit the reset button to reboot the computer. Does this mean I can't overclock any higher because the power supply can't give out any more power because it's at it's limit?

 

[tuesday0180]

Your psu does not have 38a. You can't just add the rails up like that, it doesn't work that way.

Normally the formula is : maximum total combined wattage on the combined 12v rails divided by 12 = amp rating for psu

I really can't say what the problem is, you have not even mentioned temps.

What are your cpu and gpu temps under load?

You could try another psu.

CPU load hits 50c as the highest while playing bad company 2. Idles around 31-34c depending on room temperature.

GPU load hits 91c if I leave the fan on auto and stays around 64c if I put fan on 100%.

 

[Onus]

Running the GPU fan at 100% will shorten its life; I'd back it down to 80% if possible.
zzfh is also right about your PSU. Furthermore, it's a Thermaltake, so it probably isn't capable of outputting what's on its label anyway. Your immediate crash sounds more like the PSU than overheating; if the GPU were getting too hot from your OC, you'd probably see artifacts and then a crash, but the sudden crash is likely because your PSU can't hold up its end of the log.
For a [strike]space heater[/strike] Fermi, you want a 600W-650W PSU, but it needs to be a quality one, like Antec, Corsair, PC Power & Cooling, Seasonic, or Enermax.

 

[gsturbo420a]

jtt is right. if you only have a 600 watt PSU and you have all kinds of other *** ie: 4 HDD, CPU, RAM, CD drives, case fans everywhere, etc, it may not be getting enough power. Those temps aren't bad being overclocked that much. 91c is so so. Much happier with my ati 5850 OC'd at 975 core and 1300 mem peaking at 70c Then again, you may have just hit the wall. If i go to 980 core, it crashes. PSU is fine, 850 watt. It just isn't stable anymore regardless of voltage. Try upgrading PSU, if that doesn't work, looks like you're stuck where you're at

 

[Onus]

The problem is, being a Thermaltake, it likely ISN'T a 600W PSU; it may barely be 500W. Only 38A on the +12V rail(s) is low for a good 600W PSU anyway, not that they are additive, as zzfh explained. There's a Mushkin 550W PSU out there that has a 20A limit on each +12V rail, but a combined max of only 28A; so yours may add to 38, but really only give you 32, or 30. Also, eVGA may say a system with a Fermi needs 38A total for everything, but that number will go up when you start overclocking. Allowing for eVGA's likely deliberate overestimate, even if you only need 32A, you're probably trying to pull more than that with your OC.