• 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.

4870x2 x2crossfire

Bearing in mind all the other hardware you're going to need to power I would think in terms of getting a 1kw psu. A little under that would probably be fine. Worth having a little over kill imo.
Many good brands out there, Enermax, Be Quiet, Power Pc, Corsair etc.
 
Last edited:
johny dolan said:
Dont get less than a 1000 watter.My enermax galaxy would do or any other top brand 1000 + watts. http://www.guru3d.com/article/radeon-hd-4870-x2-review-crossfire/6
Click to expand...

You have to bear in mind that they've more than likely measured the power draw from the wall.

A PSU drawing power from the wall will always be more than it's outputting to the components. a 1000w PSU is complete overkill.

Even if an X2 crossfire set up is drawing 740w from the wall, it's still outputting much less than 700w. I'd guess it would be outputting around 650-680 to the PC components.

Don't forget, a 1000w PSU running at full pelt (that's outputting 1000w to the components) will be sucking more than 1000w from the wall.

What it will draw from the wall is dependant on the efficiency of the PSU. If the PSU was rated at 20% efficency, that means 1000w is 80% of what the PSU is drawing from the wall. That means that the PSU will draw up to 1250w from the wall at full capacity.

Anyway, my point is that people often mix up their numbers when it comes to suggesting a power supply to get and assume that they draw what they're rated at, as in an 800w PSU would be close to its limit if it was drawing 750w from the wall, when in reality it's actually got quite a bit more left in it.

That guru 3D review shows that you could just scrape by using a 600w PSU. I'm not recommending a 600w of course, but a 1000w is wasted money in my opinion, you could get a perfectly capable PSU that would see you by for a good few years for a lot less than the cost of most 1000w PSUs.

A 750-850w will be perfect for your needs.

Antec True Blue 750w £98

Corsair 750w £115

Zalman 750w £119

To be honest though, I think 2 4870X2s is completely unnecessary considering ATi's new cards are due in around 2 months. By the time a game comes out that needs the power of 2 X2s they'll be obsolete and basically a waste of money.

If you want an X2, I'd advise you to get one, if you can wait get something a lot cheaper than a 4890 and wait for radeon 5 series, you'll end up with a much better gaming PC then.
 
I think its a bit overkill unless your gaming at 2560x1600 i dont think you'll see that much of a gain althou PSU wise id go for this or for a bit more peace of mind this
 
Last edited:
I cant comment on the technical aspect, but I can confirm from personal experience that my rig will not work with 2x4870x2s and an Enermax 720W PSU

It runs fine with a 1000W Corsair ;)
 
~TB~ said:
I cant comment on the technical aspect, but I can confirm from personal experience that my rig will not work with 2x4870x2s and an Enermax 720W PSU

It runs fine with a 1000W Corsair ;)
Click to expand...

The reason more than likely being the PSU's amperage ratings rather than its wattage ratings.
 
Quite possbly, as I say im not qualified to comment on the technical aspect but an Enermax Liberty 720W fails where the COrsair HX1000 works :D
 
If the op wants to run h2o and half a dozen HDs and lots of fans ect it pays to have power in hand.Running a psu balls to the wall 24/7 is not something id recommend.My enermax galaxy is also 85% efficient.I prefer to work out what i need and get a extra couple o hundred watts extra.
 
johny dolan said:
If the op wants to run h2o and half a dozen HDs and lots of fans ect it pays to have power in hand.Running a psu balls to the wall 24/7 is not something id recommend.My enermax galaxy is also 85% efficient.I prefer to work out what i need and get a extra couple o hundred watts extra.
Click to expand...

My point really was for them to just make sure they know what they're getting and to make sure they don't spend £180-£200 on a PSU that will never get used to its full potential (as in new standards come out in a few years meaning it needs to be swapped for a newer PSU).
 
Have you run two 4870 x2s with a tagan 800 watter gareth ? TB said Enermax Liberty 720W fails where the COrsair HX1000 works with his cards.Guru measured the power as 740 watts with a air cooled core duo.Most likely the op will run quad overclocked and maybe h20.If you measure and it uses 750 to 800 watts draw then i dont think telling the op to buy a 800 watter is good advice.If it does run with a 800 then it will be running flatout or close to all the time its under load.When building a pc you should never ever skimp on the psu as that is the most common cause of pc problems.If the op is spending the money to buy top performance gfx cards why risk ruining the performance for the sake of saving a few quid on the psu.Also every year the power needed for new cards increases so a good psu with power in reserve is a good investment.If you were buying a car and wanted one to do 70 mph alday on the motorway you wouldnt buy a car with a top speed of 75 would you.
 
johny dolan said:
Have you run two 4870 x2s with a tagan 800 watter gareth ? TB said Enermax Liberty 720W fails where the COrsair HX1000 works with his cards.Guru measured the power as 740 watts with a air cooled core duo.Most likely the op will run quad overclocked and maybe h20.If you measure and it uses 750 to 800 watts draw then i dont think telling the op to buy a 800 watter is good advice.If it does run with a 800 then it will be running flatout or close to all the time its under load.When building a pc you should never ever skimp on the psu as that is the most common cause of pc problems.If the op is spending the money to buy top performance gfx cards why risk ruining the performance for the sake of saving a few quid on the psu.Also every year the power needed for new cards increases so a good psu with power in reserve is a good investment.If you were buying a car and wanted one to do 70 mph alday on the motorway you wouldnt buy a car with a top speed of 75 would you.
Click to expand...

Did you actually read my post? If an 800w PSU draws 800w from the wall it's not at its limit. :confused:

If it's an 80% efficent PSU then it's going to be outputting 640w, that's not at its limit at all.

To make it clear, an 800w PSU working flat out at 20% efficiency will be drawing 1000w from the wall. It's not hard to follow.

The fact that you compare it to a car on a motorway shows you don't really understand how to spec a PSU for a PC.

If you look at the Guru3D review, you'll realise that it was 740w from the wall, that means the absolute minimum PSU for dual X2s is 600w.
 
Last edited:
Not all psu are created the same.When i bought my first gtx 8800 i had a tagan 470 and thinking that might struggle i got a enermax 620 to go with it.The enermax crashed everytime i ran a benchmark and wasn't man enough to run the card.I swapped my tagan 470 back in and that ran the card fine.Its just wiser to buy more power than you need as the ratings dont tell the whole story.I later passed on the 8800 and tagan 470 to my brother but the psu failed after 6 months or so and took out the gfx card with it.If the op buys a 800 watt psu and it wont run the cards then its a pain to send it back and get another psu and fit it again.Its even more of a pain if it goes boom and takes out the rest of the pc with it.The op can read the thread and make his own choice.
 
You must log in or register to reply here.
Back
Top Bottom