Corsair ax750wt or ax860wt for SLI GTX 670?

[poohbear]

Hey all, debating between the Corsair AX750wt or AX860wt (both Platinum 90%+ efficiency) for my SLI GTX 670s, i currently have a 520wt PSU and it aint cutting it according to the SLI requirements of SLI GTX 670s.

Now, 750wt will work fine, but will 860wt be better because ideally u want the system to be running @ 50% of total wattage for optimal efficiency, no? SLI 670 with my 2500k @ 4.4ghz will consume around 480wts, so 860wt will have it closer to 50% efficiency yea? its a $30 difference between both PSUs & i'm pretty sure i'll be keeping the PSU for atleast 5-6 years.... whattaya think?

Edit: i'm reading some people experience coil whine on the ax860, anyone that owns one experienced this or has it been fixed?

 

[lehtv]

For 670's, the 750W unit is definitely more than enough. Even a good 650W unit would run it fine.
http://www.guru3d.com/articles_pages/geforce_gtx_670_2_and_3way_sli_review,4.html
"System Wattage with GPUs in FULL Stress = 433W"

Now, 750wt will work fine, but will 860wt be better because ideally u want the system to be running @ 50% of total wattage for optimal efficiency, no?

Not really, the difference in load-efficiency between the 750W and 860W units would be <1%. That is not even close to being enough to pay back the difference in up front cost in a reasonable amount of time.

Also, having a higher wattage unit would have the effect of lower efficiency on idle which would balance the higher efficiency at load.

 

[poohbear]

good points, thanks for clarifying lehtv. i'll save the $30 & go with the 760wt.🙂

 

[Z15CAM]

XFX Pro 750W Black Edition for under $100 at NCIX. Same as Seasonic and Corsair KM3 design. It doesn't appear the suffer the Coil Wind issue as reported by some Seasonic owners.

You can pick up a XFX Pro 850W Black Edition for under $125. I presently own one of these and must say it's the Best PSU I've ever owned and I've owned several Seasonics.

Both are Gold/Platinum.

Here's a Review: http://www.hardwaresecrets.com/arti...Edition-Full-Modular-Power-Supply-Review/1695

 

[poohbear]

damn i upgraded to the ax760 and the coil whine is unbearable (its on all the time). its a high pitched whine and i have a case with alot of openings at the the top and the computer is in my bedroom, so it has to go back. gonna exchange it for a seasonic (eventhough this corsair ax760 IS a seasonic psu!)

 

[Nec_V20]

Edit: i'm reading some people experience coil whine on the ax860, anyone that owns one experienced this or has it been fixed?

I own two AX860 PSUs one of which has been running for about three months now and I have not experienced any coil whine. The other one has only been hooked up to test that it is running all right for 24 hours, as it is going into a machine I am building for myself at present. But again I did not notice any noise from it at all.

I got very lucky and managed to find the AX860s on sale cheaper than any AX750, AX850 or AX760 PSUs it was just a smidgen more expensive than the TX750.

I also have an AX850 which has been running in my main machine 24/7 for 995 days 13 hours and it is completely inaudible.

I had a lot of bad experiences with PSUs after my move from Germany to the UK in 1998. And those PSUs were not by any stretch of the imagination cheap ones. The UK power grid (at least where I live) is a lot more prone to surges than where I lived in Germany.

One power surge in the house I live about half a year ago did cause the AX850 to stop, the same surge took out two PSUs and one motherboard of my two neighbours in the house. After pulling the plug leaving it for about ten minutes and connecting it up again the AX850 was as good as new.

They know I am a computer techie so they came down to see if I could help (of course it happened on a Sunday).

I had a couple of spare PSUs lying around and I installed them in my neighbours PCs.

One of them came back up again but not the other.

Here is the funny part of it. I had an old Tyan 775 which had been kicking around my place for years. I had even trodden on it once with my bare foot and the IDE pins punctured my skin and it had quite a lot of my blood on it. I got out the trusty Isopropanol, gave the board a clean, straightened out the pins, put my neighbours CPU into it, hooked it all up and was amazed that the thing booted.

Talk about indestructible - they should have called it the "Tyan Captain Scarlet" :biggrin:.

 

[poohbear]

thanks NEC V20, i exchanged the ax760 for a 2nd one and unfortunately that had coil whine too!😛 I even tried it on a 2nd system but same problem. I went back and opted to get a Seasonic 760 (SS-760XP2) and FINALLY no coil whine! 🙂

Turns out the ax760 was based on the KM3 Seasonic (X series) and they were notorious for coil whine. The SS-760XP2 has more glue used on capacitors from what i've read, and thus coil whine doesn't occur. Loving my new SILENT psu!🙂

 

[Nec_V20]

thanks NEC V20, i exchanged the ax760 for a 2nd one and unfortunately that had coil whine too!😛 I even tried it on a 2nd system but same problem. I went back and opted to get a Seasonic 760 (SS-760XP2) and FINALLY no coil whine! 🙂

Turns out the ax760 was based on the KM3 Seasonic (X series) and they were notorious for coil whine. The SS-760XP2 has more glue used on capacitors from what i've read, and thus coil whine doesn't occur. Loving my new SILENT psu!🙂

I wrote in my post above:

it was just a smidgen more expensive than the TX750

That was wrong, I meant to write "it was just a smidgen more expensive than the HX850".

I was originally wanting to buy a TX750 for the NAS I was building when I came across the offer for the AX860. When I compared that price to the prices being asked for the AX750, AX760i, AX850 and HX850 that I could find I decided it was too much of a bargain to pass up.

"Just a smidgen more expensive than the TX750" would not only have been a bargain but a sure indicator that the AX860 came off the back of a lorry. Sorry about that. :$

Be that as it may, I had read of reports of coil whine with regard to the AX860, there are a number of them on the Corsair forum.

It's possible that Corsair reacted and got Seasonic to rectify whatever error caused it so that I am not affected and those who are still affected are unlucky enough to be purchasing them from an older batch.

I put a jumper into the AX860 I have had running in my NAS, so that it was just running on its own and it is absolutely silent.

 

[poohbear]

yes i think it was an older batch cause usually corsair is spot on. Seasonic had that problem across their KM3 (the X series) line. anyways, this Seasonic 760 is silent as hell and has specs out of this world, so i'm happy.🙂 it has a 7 year warranty and i intend on using it for 7+ years like i did with my Corsair HX520 (well had that one for 6 years, only replacing it cause i'm going SLI). In 7 years @ 92%-94% efficiency it'll MORE than make up its cost.🙂