Quote from: nachius on August 30, 2013, 02:17:49 PM

Quote from: Frogwithcancer on August 30, 2013, 01:04:59 PM

Hi there

I'm currently running a 6850 and a 5850 on a 600W Corsair PSU in:

Corsair 600W CX Builder Series 80 Plus PSU
Core i7 2600k
Corsair Vengeance 8GB (2x4GB) DDR3 1600Mhz
Gigabyte GA-Z68X-UD3-B3 Z68 Socket 1155
Arctic Cooling Freezer 7 Pro rev 2 Socket 1155
1 SSD
1 HD (7200)
3 120 MM fans
1 140 MM Fan
1 DVD RW

Will i be ok to replace my 5850 with a 7950 and keep using the same PSU or am i going to have issues?

Also what happens if you draw too much power from your PSU does it shut down or blow?

600 watt isn't going to cut it...
You would push close to 600 watt for the whole system with just the 7950 overclocked (almost 400 watt [369 watt battlefield load tested] use for the card itself) pushing full load, a non overclocked version will push 250 watt [235 watt battlefield load tested] system draw as well. Add in the 6850 at around 250 watt (229 watt 3dmark06 tested) and you're asking for disaster.

Power is very important and it can behave is unexpected ways meaning a simple shut down because too much load to the extremes of blowing multiple parts in your system and at the far end of the spectrum and rare but possible causing a fire.

I'm going to disagree with you here. I believe you can power a 7950 and a measly 6850 off of your 600 watt PSU. There is not a snowballs chance in hell that a 6850 uses 250 watts. You need to get your kill-a-watt figures right. Get in a proper baseline load with no GPU and baseline 100% cpu load with no GPU before you start throwing GPUs into the mix and deciding what uses what amount of power.

IMO, I don't believe a setup as yours uses much more than 60 watts while idling (An MSI Z77A-G45 motherboard with dual core sandy bridge celeron, 2x2GB RAM, hard drive, keyboard, and mouse used 25 watts at the wall for me for comparison while idling). A fully loaded 2600K worst case scenario is an additional 140 watts on top of that using linpack which is designed to max out CPU power in any way shape or form; typical max loads probably won't see more than an additional 100 watts on the CPU though so we'll say 100 watts, so assume 160 watts fully loaded baseline.

An idling 7950 will use about 20 watts (or 1 watt if it is an unused secondary card due to zero power technology). An idling 6850 will likely use about 10 watts. Fully loaded 7950 (200W TBP) with +20% powertune is 240-250 watts, and a fully loaded 6850 (127W TDP) with 20% powertune is ~150 watts. Adding up all those figures, we get 560 watts, or if you happen to be running linpack as well, we get the magical 600 watts.