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Hi guys, I've taken the plunge and started building a rig as a little fun test. It's all running but I've had to underclock my new Radeon Sapphire 9750 by two thirds to get it to run without overheating (and this is with a box fan pointed at it and the card fans turned up to 100% too). This obviously isn't normal as people game and mine with these cards all the time.

Can anyone advise if a cpu or psu upgrade has any bearing on the ultimate temperature of the card? Thanks in advance.

It seems to shut down around 50 degrees c or 130 degrees f if that helps. I have no idea if that seems right as this si the first time I've delved into system temperatures.

50 degrees Celsius seems way too cold, my card consistently runs around 80 degrees Celsius

If it's 50 C when it shuts down it isn't overheating. My GPU gets over 90 C without crashing. I think it may be your PSU not delivering enough power.
How many watts is your PSU?

0) kill all programs or make a clean boot
1) launch GPU-Z, select your video card, look at +12V indicator and all the temperatures
2) launch miner or FurMark or anything else which loads GPU hard on the card you are watching in GPU-Z

If temperature jumps a lot, like from 40 to 80 - replace thermal grease
If temperature is rising slowly but reaches 90+ - replace fan, add additional fans etc.
If +12V drops below 11.5V - replace PSU
If there is no +12V indicator in GPU-Z, try SpeedFan

Thanks so much guys, I'll try this all today and let you know what happens. The PSU is 500w so pretty weak for such a beast of a card I guess. Thanks again, I'll post back later today.

Okay, the +12v sits at 11.552v when 'idle' and drops to 11.491v when using guiminer with the underclocked card and 11.43v when the card runs at it's normal settings. Now I'm aware of this I can actually hear a dip in 'hum' of the fans etc when I hit to run giuminer which I guess is all due to the lack of power. What shall I jump to? 800w-850w?

you mean 7950

That's the one  :D

Before buying a new PSU, try to undervolt the cards. If you can, 500 W should be enough.
I have 2 7950s running 1050 MHz, undervolted to 0.988 v, the power consumption are around 120-150 W per card.

Thank you. I've been running the card underclocked to the max today just so it can be doing something, undervolting has allowed me to push another 100 Mhash/s out of it so thanks very much for the tip. Currently running at 250 Mhash/s which will do while I look into the PSU situation I guess.

I haven't really experienced with underclocking, but the power consumption should be minimal (a few 10 watts) between say 600 MHz and 950 MHz. Try to raise clock to 900, with undervolting. If it holds stable, then try some more. :)
I get 550 Mh/s / card out of the 7950s at 1050 MHz with undervolting.

Great, I've had a play around and after a few crashes I've found the ratio it likes the best- Clock 750 with 950 vddc. I'm now getting 380 Mh/s  ;D Thanks again Vega.

Throw your PSU away immediatly, it's very close to being defective! ))
Even at idle it is very low voltage.
11.43 is barely within the specs +/-5%, that's between 12.6 and 11.4
I suspect that capacitors inside the PSU are bulged or will be soon. Their ESR is already through the roof probably.

As for PSU power, I have PC with Core i5(dunno) + GTX 560(150W off. spec) + HD 7950 220W(measured by me) + Thermaltake 600W PSU.
I've tested it - 7950 is hashing LTC at ~600 khs, GTX 560 - Furmark and Core i5 - prime95, +the lowest value for 12V in both GPU-Z and SpeedFan is 11.95V
I've even tried swapping GTX 560 with 6950 (220W) and 12V was showing ~11.90V
I've confirmed readings with multimeter and run tests for several hours.

So. You need good working PSU, not powerfull. I can recommend Seasonic or Enermax, they are expensive though.

As soon as I read this

I thought this

Great Answer, a junk PSU is the problem

Oh, okay :o It's really old to be honest, just started creating this rig with an old desktop as the basis. I'll order a new PSU as soon as I get paid. Thanks again for the advice. There's no 'thanks' button on this forum so, THANKS!