• Competitor rules

    Please remember that any mention of competitors, hinting at competitors or offering to provide details of competitors will result in an account suspension. The full rules can be found under the 'Terms and Rules' link in the bottom right corner of your screen. Just don't mention competitors in any way, shape or form and you'll be OK.

6870 CF

uksoldierboy

uksoldierboy

uksoldierboy

Soldato
Joined
6 Aug 2009
Posts
4,504
Location
Wales
Hi all,
just a quick question, me and a friend are debating over modern day gaming rigs and their power needs.
I just bought two XFX 6870s for CF duties and my friend seems to think that because "according to the tech specs" a single card, so he reckons use 421 watts, two would use 842 watts in CF, i disagree and i was just wondering if some of you guys with far more experience could help straighten things out.

many thanks
david
 
just out of interest (and sorry to hijack) whats the single card equivalent of CF6870's on say a Q6600 @ 3.4?
 
7950 maybe? Really depends on resolution (due to VRAM limits). TBH, avoid crossfire if you can due to microstuttering, heat and power issues. Single cards might be slower in raw FPS terms but you'll get smoother FPS. You really only use SLI/crossfire to get better quality AA or whatever if your card can already achieve synchronised framerate.
 
I also have 6870s in crossfire and they beast every game i chuck at them, incredible fps at the highest settings. When i bought them it was the best bang for buck compared to single cards of the same calibre. That being said it looks like the market is trending in the single card setup so i would have to say sticking with AMD the single card option that would be worth buying over 6870 crossfire would have to be one of the 79** series.
This is an option i am seriously considering for the reasons explained in the previous post.
 
uksoldierboy said:
thanks for the info guys, so just to confirm, 6870 in CF will not use 842 watts like my friend seems to think?
thanks again.
Click to expand...

Each card has two 6 pin PCI-E connectors, which can supply a maximum power of 75W each. PCI-E 2.0 connector supplies 75W giving a total of 225W maximum that the card can possibly draw. Two cards = maximum draw of 450W. In reality, each card at stock only draws 150W, so two = 300W. You'll reach the overclocking ceiling at 1050 mhz well before you hit the power limit of the connectors, and it's uncommon unless you have a non standard cooler that you'll get over 1Ghz anyway.
 
uksoldierboy said:
thanks for the info guys, so just to confirm, 6870 in CF will not use 842 watts like my friend seems to think?
thanks again.
Click to expand...

No it will not. The PSU is also powering other items in the PC like the CPU (typically 65-130W), the motherboard plus all the stuff attached to it and then there's hard drives etc.

You can roughly work out each graphics cards max power consumption by a bit of simple maths. The PCI-E slot provides 75W (ignoring the PCI-E 2.1 thing) plus 75W for each 6 pin power connector or 150W for each 8 pin power connector on the card.

As stated previously a 6870 requires approx 150W going flat out (even though most have 2x6pin power sockets)

Google Power Supply Calculator, there are a number of sites where you can select the components and it'll estimate the power supply required with a suitable safety margin.
 
You must log in or register to reply here.
Back
Top Bottom