Overclock.net › Forums › Graphics Cards › AMD/ATI › 850w PSU strong enough for 6970 CF setup
New Posts  All Forums:Forum Nav:

850w PSU strong enough for 6970 CF setup - Page 2

post #11 of 13
Thread Starter 
Thanks for the quick replies. This is great because I can get that PSU for under $100. I forgot to add that I'll be going with an ASUS maximus extreme IV motherboard. I can already sense that this community is going to be awesome to hang around.
My System
(15 items)
 
  
CPUMotherboardGraphicsRAM
Intel i7 2600k @ 4.6GHz [1.312v] ASUS MAXIMUS IV EXTREME Crossfire 2xMSI Radeon HD 6970 G.SKILL 16GB (4x4GB) Ripjaws X Series 
Hard DriveOptical DriveCoolingOS
Corsair Force Series GT 120 GB Asus DVD Burner Noctua NH-D14 Windows 7 64bit 
MonitorKeyboardPowerCase
30" Dell U3011 Steelseries 7G XFX 850W Black Edition PSU Haf X 
MouseMouse PadAudio
Razer DeathAdder SteelSeries Icemat I2 Blue Asus Xonar STX 
  hide details  
Reply
My System
(15 items)
 
  
CPUMotherboardGraphicsRAM
Intel i7 2600k @ 4.6GHz [1.312v] ASUS MAXIMUS IV EXTREME Crossfire 2xMSI Radeon HD 6970 G.SKILL 16GB (4x4GB) Ripjaws X Series 
Hard DriveOptical DriveCoolingOS
Corsair Force Series GT 120 GB Asus DVD Burner Noctua NH-D14 Windows 7 64bit 
MonitorKeyboardPowerCase
30" Dell U3011 Steelseries 7G XFX 850W Black Edition PSU Haf X 
MouseMouse PadAudio
Razer DeathAdder SteelSeries Icemat I2 Blue Asus Xonar STX 
  hide details  
Reply
post #12 of 13
this is more than enough. even with OC headroom it will handle it and then some
post #13 of 13
Quote:
Originally Posted by TDS View Post
You will be more than good. Check my sig rig out.. I am running a HX 850... and with a kill a watt meter.. I pull max 520watts

I would suggest the Corsair over the XFX one you listed though.. at least in my research when I recently upgraded for Xfire.. I found the XFX to be lacking in connections.
This.

When talking about power draw at the wall (when talking about using a meter like the Kill A Watt), we're talking about a power draw that's higher than the power that the system is pulling from the power supply because the PSU is not 100% efficient.

So let's pretend that the efficiency at the time of this 520W power draw at the wall was 85%. If that were the case, then the system was pulling 442W from the PSU which means his PSU (the HX850) has more than twice the power capacity he needs for this particular power draw.

To clarify it further, let's say the efficiency was 80%. If it were, then that would mean the system was pulling 416W from the power supply at that time.

Now, AMD recommends a 550W peak-rated PSU to power a system with a single 6970 in it (proof). Now, most of these pages on AMD's site that show this also show the recommendation for the same card in Crossfire. This one doesn't, but every page I have ever seen where the Crossfire recommendation is mentioned, it's always exactly 100W more for the Crossfire recommendation. So this means that I believe AMD would recommend a 650W peak-rated PSU to power a system with two 6970s in Crossfire.

So this would mean that a 650W continuous-rated PSU (such as the HX650) would be more than enough, and I think TDS proved it with his 520W power draw at the wall.

In other words, save some money and get a good 650W or perhaps a good 750W at the most if you don't believe us and need peace of mind. But a quality 850W would be unnecessary extreme overkill and it would even result in a lower efficiency due to the smaller power draw on such a PSU as compared to that of a quality 550-750W. Generally speaking (very generally, here), PSUs are at their most efficient when under a 50% power draw. So since we aren't putting 50% load on our PSUs at all times, it's best to buy a PSU where the load on the PSU while gaming is at least 60-75% or perhaps even more. That way, the average efficiency is maximized.

Here's more information on efficiency:

On PSU Efficiency
PSU "50% Load" Myth

More articles
It's a computer!
(19 items)
 
  
CPUMotherboardGraphicsRAM
i5-2500K @ 4.5GHz (1.368-1.384V fixed voltage) ASUS P8P67 EVO B3 (UEFI ver. 1850) GTX 780 ASUS DirectCU II (1228 / 6300, 1.180V) G.SKILL Ripjaws X 8GB (2 x 4GB) 1866MHz, CL9 
Hard DriveHard DriveHard DriveOptical Drive
250 GB Samsung 840 EVO (C:\) 250 GB Samsung 840 EVO (D:\) 150 GB WD VelociRaptor Samsung SH-S243N 24x DVD Burner 
Optical DriveCoolingOSMonitor
Samsung SH-S203N 20X DVD Burner Thermaltake Frio Win 7 Home Premium x64 SP1 Retail AOC G2460PG (24" 1920 x 1080 144Hz G-SYNC) 
KeyboardPowerCaseMouse
Filco Majestouch 104-key Cherry MX Blues w/NKRO Corsair HX650 (Bronze, ordered on 12-12-2009) CM 690 Intellimouse Optical (1.1A) 1000Hz polling rate 
Mouse PadAudioAudio
Basic, but premium round X-Fi Titanium HD Klipsch ProMedia 2.1 (with 16 AWG Monster Cable... 
  hide details  
Reply
It's a computer!
(19 items)
 
  
CPUMotherboardGraphicsRAM
i5-2500K @ 4.5GHz (1.368-1.384V fixed voltage) ASUS P8P67 EVO B3 (UEFI ver. 1850) GTX 780 ASUS DirectCU II (1228 / 6300, 1.180V) G.SKILL Ripjaws X 8GB (2 x 4GB) 1866MHz, CL9 
Hard DriveHard DriveHard DriveOptical Drive
250 GB Samsung 840 EVO (C:\) 250 GB Samsung 840 EVO (D:\) 150 GB WD VelociRaptor Samsung SH-S243N 24x DVD Burner 
Optical DriveCoolingOSMonitor
Samsung SH-S203N 20X DVD Burner Thermaltake Frio Win 7 Home Premium x64 SP1 Retail AOC G2460PG (24" 1920 x 1080 144Hz G-SYNC) 
KeyboardPowerCaseMouse
Filco Majestouch 104-key Cherry MX Blues w/NKRO Corsair HX650 (Bronze, ordered on 12-12-2009) CM 690 Intellimouse Optical (1.1A) 1000Hz polling rate 
Mouse PadAudioAudio
Basic, but premium round X-Fi Titanium HD Klipsch ProMedia 2.1 (with 16 AWG Monster Cable... 
  hide details  
Reply
New Posts  All Forums:Forum Nav:
  Return Home
  Back to Forum: AMD/ATI
Overclock.net › Forums › Graphics Cards › AMD/ATI › 850w PSU strong enough for 6970 CF setup