5870 Crossfire.. i7 920 OCed

[Grooveriding]

Hiya, I'm expecting my second 5870 to arrive on Monday.

I have a PCP&C 750W Silencer in my rig... rig is

i7 920 oced to 4.2 at 1.31v
6gb ram
hard drives, 120mm fans etc.

Going to add the second 5870 for CF. I've checked the PS calculator pages and looks like my PS will handle it.

Just looking for some confirmation from some folks in the know on PS. Please no overkill suggestions, I only want to upgrade to something more powerful if I -have- to. I think my PS is enough, just looking for some advice/confirmation that it is.

Thanks in advance!

 

[HOOfan 1]

how many hard drives?

Your PSU should be enough

 

[Grooveriding]

Originally posted by: HOOfan 1
how many hard drives?

Your PSU should be enough

One SSD, and 5 SATA drives.. I have other rigs I can put the drives into though. I also have 11 120mm Fans

Should of mentioned that as well, I know without those fans and so many hard drives it's a definite on my current PSU. My main worry is will I damage anything in my rig by trying to add the 5870 and finding out my PSU is not enough ?

Or will my system just crash. I'd prefer to avoid spending the $200+ CDN it will cost to buy a quality PSU in 1000W. I know my current PSU is high quality, hoping it can handle this ...

 

[HOOfan 1]

you wouldn't need 1000W anyway. No you likely won't damage anything, it will just restart or lock up.

I think with that many fans and HDDs you will be toward the upper limit of your PSU...but it still should work. If it doesn't then go out and buy something in the 850W-850W range.

 

[lavaheadache]

what are you running that needs 5870 crossfired?

 

[Ayah]

The PC P&C is way more than overkill for a normal overclocked CF system.

 

[Meghan54]

Originally posted by: Ayah
The PC P&C is way more than overkill for a normal overclocked CF system.

I wouldn't call a 750W power supply way overkill for a i7 920 system w/Crossfired 5870's.

An i7 920 overclocked to his speed of 4.2GHz will easily draw more than 200W. And as Anandtech's testing showed, an i7 920 rig, which was OC'd to only 3.33GHz at stock voltages, with a Crossfire setup of 5870's drew over 650W at full tilt....I think "way more than overkill" is a bit over the top as a comment and is instead more misleading.

 

[Ayah]

Originally posted by: Meghan54

Originally posted by: Ayah
The PC P&C is way more than overkill for a normal overclocked CF system.

I wouldn't call a 750W power supply way overkill for a i7 920 system w/Crossfired 5870's.

An i7 920 overclocked to his speed of 4.2GHz will easily draw more than 200W. And as Anandtech's testing showed, an i7 920 rig, which was OC'd to only 3.33GHz at stock voltages, with a Crossfire setup of 5870's drew over 650W at full tilt....I think "way more than overkill" is a bit over the top as a comment and is instead more misleading.

I guess not "way" overkill, but it's still more than enough to safely run his rig.

 

[v8envy]

Originally posted by: Meghan54
And as Anandtech's testing showed, an i7 920 rig, which was OC'd to only 3.33GHz at stock voltages, with a Crossfire setup of 5870's drew over 650W at full tilt....I think "way more than overkill" is a bit over the top as a comment and is instead more misleading.

Was it drawing 650 watts from the wall? I can see a ~80% efficient PSU drawing that much from the wall to output ~500 watts needed to power that sort of rig. A 250 (out of 750) watt cushion would be in the realm of "overkill", and in absolute terms even "massive."

But with OP's 6 drives and 11 fans (estimated 80 watts peak) and capacitor aging it's definitely approaching the rated output of that PSU. I wouldn't be afraid to try it though.

 

[AznAnarchy99]

11 fans? my god

 

[Patrickz0rs]

Originally posted by: lavaheadache
what are you running that needs 5870 crossfired?

I would also like to know this + why 11 fans lol wow.

 

[MagickMan]

Originally posted by: AznAnarchy99
11 fans? my god

What did you say?!?! I couldn't hear you over the roaring of those fans!!! :laugh:


OP, the PCP&C unit is fine for what you're doing.

 

[Suspicious-Teach8788]

Originally posted by: MagickMan

Originally posted by: AznAnarchy99
11 fans? my god

What did you say?!?! I couldn't hear you over the roaring of those fans!!! :laugh:


OP, the PCP&C unit is fine for what you're doing.

11 fans is an issue if you have delta fans going. I got 12v 0.3A fans (~80cfm each). 4W x 11 adds up but usually I don't even care if I have 3-4 fans. That's so little wattage it doesn't matter.

 

[Belmont]

I am running CF HD5870s w/ a Phenom II @ 1.45vcore and my cards are OCd to 900/1300 - I had power issues running at full load w/ my 750w PSU so I upgraded to a 1000w OCZ and it doesn't randomly grey screen anymore (which was a side effect of hte cards not getting enough power)...now when you guys talk aobut the PSUs the overall wattage doesn't matter much..what really matters is how much the 12v rail can supply, my old PSU had[+3.3V@25A,+5V@30A,+12V1@25A,+12V2@35A,-12V@0.8A, +5VSB@3.0A] and I upgraded to[+3.3V@25A,+5V@25A,+12V1@83A,12V@0.8A,+5VSB@6.0A] and if you look at that 12v rail that is what really matters, so if your current 12v is lower than my old one you might want to upgrade

 

[HumblePie]

Me, I have 2x 4870x2 with an I7 Oc'd to 4Ghz, an OCZ vertex SSD, a velociraptor, and a couple of 1TB drives. I also have a couple of blue ray combo optical drives.

I know for a fact the power even a single 4870x2 is higher than two 5870's in xfire.

I am also running a Antec 850 watt Quattro. It is just a little more juice but still running fine.


The only reason I am tempted to upgrade my PSU is because I want a good confirmed GOLD efficiency one. And if I am going to upgrade for that, I am going to upgrade big time of course.

 

[Belmont]

I know for a fact the power even a single 4870x2 is higher than two 5870's in xfire.

lol.

 

[Grooveriding]

I would also like to know this + why 11 fans lol wow.

I have a HAF 932 for a case.. I changed out all the fans. I have two 120s on the top, two 120s in the front, 4 120s on the side, 1 120 in the back, and 2 120s on my cpu heatsink.

Just as an update, I ended up having to upgrade the PSU. Went with a Corsair 1000HX. :awe:

 

[yh125d]

That's definitely the upper limit, but it will work. If you plan on adding more HDs or fans or overclocking more though you're gonna want to upgrade