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HD5770 crossfire psu help

Last response: in Components
February 10, 2010 9:42:35 AM

Hi all,
I am looking at having a Asus Hd5770 Crossfire setup running with Asus M4aXTD-evo and the AM3 Phenom II955, Still not sure what ram i will be using yet.

The problem is i was looking at the requirements for the 5770 crossfire and a 650w psu would be fine with wattage left over, but i am not sure on the amps that come with the psu's.

I was looking at the tx650 Corsair as it has got some good reviews but it only has 52 amps on a single 12+ rail, im not sure what all these rails mean and not sure if one, two or four rails are better.

the requirements for the 5770 in crossfire is min 55 amps.

Any help would be great and opinions on ram would be great too.


More about : hd5770 crossfire psu

February 10, 2010 10:50:46 AM

dno much about what you'll need, but what i know is corsair psu's does it well.. using a 400W in an e6600 + ati 4850 and 4hdds.. and i'll bet this psu could pull alot more..
February 10, 2010 10:55:21 AM

er - do you already own one x 5770? And you are going to buy another to crossfire? Or are you thinking of doing a new build?

If you are thinking of doing a new build I would just buy a single 5850. Its just as fast as 2x5770 and probably slightly cheaper. Plus you dont have to worry about games which dont have great scaling in crossfire modes. I.E. it is more likely to give better framerates in a wider selection of games.

To answer your question - if I had a Corsair 650watt PSU I would use it to crossfire 2 x 5770 with great confidence. And I would use it to power 1 x 5850 with even more confidence. Corsair PSUs are the bomb. They often test much higher than they are officially rated (i.e. 650watt Corsair will prob do >700 watts no problem)

Should work fine!

As for the RAM I dont know, im using socket 775 :S
But corsair make good RAM too, or Mushkin - they're supposed to be good :) 
Unless you're planning to overclock I wouldnt worry too much about getting expensive RAM, and compatible RAM should do.
This is your motherboard?

Looks like you need probably a 4Gb kit of DDR3 PC3 10600 or suchlike.
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February 10, 2010 11:18:41 AM

Hi all,
Im just getting the rest of my budget together and i will be ordering the parts, i was looking at getting the corsair dominator ram 4gb (2x2gb) 1600mhz.

i have not got any of the parts as yet but i will be putting in a 8800gts 640mb oc bfg for a while.

Yes i will be over clocking when needed but this board supports 1600mhz without overclocking as someone pointed out to me in another thread.

I was getting the 5770 and then a second one down the line, but wanted dx11 for crysis 2 release at the end of the year, but what ever gpu i will be putting in i will be putting it in to c/f in the future and dont realy want to upgrade my psu again.

so shouls i worry about the amps on the psu (52a) when the requirements for the 5770 c/f is 55a if i go for the 5770 c/f. and what are the difference between the rails on the psu.

thanks for your help
a c 144 ) Power supply
a b Ĉ ASUS
February 10, 2010 6:14:43 PM

I do not know where the 55 amp estimate came from, but it is for a complete system, not just the video cards. A pair of 5770's needs about 18 amps at peak power draw. Figure about 10 amps for an OC'd quad core and that is less than 30 amps.

The rest of the power consumption is, figuratively, pocket change. A 650TX will have plenty of power in reserve.
February 10, 2010 6:19:12 PM

crysis 2 man?

if it is at all like the first one, you will need like 5870 and not 5850 or 5770s

now if they can get it right like warhead out of the gate, then nvm
February 10, 2010 8:52:37 PM

this is the link where i got the information from

But i didnt know that was for the whole system, but the 650tx will be fine even with added extras like fans and extra hdd.

Yes i understand that this system will not even run crysis on the highest settings on dx10 and will be even worse with crysis 2 on dx11 and dont know what the frame rate will be for 5770 c/f on crysis 2 but like i said i have a 8800 gts and may keep that for a while and save to get the better card/s and see how much they drop when the fermi ( i think) comes out, would you agree on that or would you go for the 5770 c/f set up

Will the higher cards single or crossfire be bottlenecked by my cpu.

Thanks for the replys guys
February 11, 2010 11:18:32 AM

wait for fermi, even if it's a crappy part, it would provoke a price drop from ati at the least

if not a whole refresh with things like the 5890 and 5790 and etc.

i would wait for it, and imo, crysis will NEVER be cpu bottled, the 955 is very capable and i'll wager that nothing now can bottleneck it and that crysis traditionally has been gpu bottleneck and not cpu

usually with good gfx, you get cpu bottlenecks at like 100+ fps so meh
February 11, 2010 6:01:42 PM

Thanks for the reply, Just a quick question i know its not in the right forum but just wanted your opinion. what ram would you get with this set up.

February 11, 2010 6:34:20 PM

well ddr3 for starters, after that, meh...

afaik, low latency ddr3-1600 is the best mix of price / performance / latency

anything higher costs an arm and a leg, anything lower may or may not limit overclocks

in 2 GB sticks that is
February 11, 2010 7:21:38 PM

I have been looking at the Corsair dominator 1600mhz, i am going to be using a asus m4axtd-evo that supports 1600mhz before overclocking.

February 11, 2010 7:24:13 PM

meh i run some cheapo ocz stuff and imo it works

i really don't care as much on ram as the other stuff, with nearly all of them offering lifetime warranty and honoring it, it isn't a big deal imo
February 12, 2010 7:38:19 AM

ok thanks for your reply
a c 248 ) Power supply
February 13, 2010 7:39:50 AM

Here are the official ATI recommended power supply requirements for the ATI Radeon HD 5770 and 5750 video cards:

450 watt or greater power supply with one 75 watt, 6-pin PCI Express® power connector recommended.

600 watt or greater power supply with two 75 watt, 6-pin PCI Express® connectors for ATI CrossFireX™ technology in dual mode.

The recommendations are for an entire pc system.

The Corsair TX650 with one large +12 volt rail rated at 52 amps is more than sufficient for powering an overclocked system with two ATI Radeon HD 5770 video cards operationg in Crossfire mode.

I followed the link you provided and took a look at the review. The Crossfire configuration used a maximum of 432 watts during stress testing. That was for the entire pc system. That is not even close to what a high quality 650 watt power supply can deliver.

The stress test revealed that a system with two 5770's maxed out at 432 watts. To determine the current (amps) simply divide wattage by 12 volts. 432 watts divided by 12 volts equals 35.25 amps.

I know why a power supply with a +12 volt rail rated at 55 amps was mentioned. It is very similar to the psu general rule of thumb I developed last year. A high quality 600 to 650 watt power supply will have a +12 volt rail rated at about 50 to 55 amps. There are low budget, low quality power supplies of questionable performance and value that people insist on buying. Those cheap psu's cannot deliver clean, stable, reliable power.

About those mutiple +12 volt rails - There are only a very small handful of power supplies that have genuine separate +12 volt rails. They are very high end, high wattage models designed for use in extremely overclocked systems with 3 or 4 power hungry video cards. It was a safety measure. The lower wattage power supplies do not have true multiple rails. At best they could be described as "virtual rails". It was an advertising gimmick. There was a big stink about it 4 years ago.

Finally the memory - Please go to the Asus web site and check the list of approved memory for your specific motherboard. Sometimes memory and motherboards do not work well together. Asus actually tests memory with their motherboards. They do not test every memory module that is available; however, they do list a good selection.
February 14, 2010 10:53:18 AM

JohnnyLucky thanks for all your help that has made it very clear.

your help has been great. thanks again
a c 243 ) Power supply
February 14, 2010 2:41:31 PM

boden08 said:

this is the link where i got the information from

Probably a typo, in other 5770 reviews ( by the same reviewer ) he claims 50 amps, I don't trust the power reccomendation's in those reviews either.

As Johhny pointed out, ATI says 600 watts and 2x 6 pin connectors, the OCZ SXS600 fits the bill with a combined 12v output of just 38 amps, but isn't Crossfire certified.

Check the list here and you'll notice a 500w psu that has been "certified" for crossfire 5770

This one
February 15, 2010 7:53:24 AM

Thanks for your reply, these are great links but i think i will stick with the corsair tx650.

thanks for your help mate
a c 243 ) Power supply
February 15, 2010 10:00:26 AM

boden08 said:
Thanks for your reply, these are great links but i think i will stick with the corsair tx650.

thanks for your help mate

Wasn't trying to steer you away from it, just reaffirming that it is more than enough.
February 15, 2010 3:07:16 PM

ok mate thanks, your post helped alot