New rig, planning 4770 CF'ing

[k0unit]

I'm building a new gaming rig, and looking to drop some money on a good PSU to last me a good amount of time. Looking to power an Asus 790GX Mobo, Phenom II X4 940, and two Radeon HD 4770's in crossfire. I will be doing some minor overclocking.

I currently have a 450W PSU, I'm not expecting it to run even one 4770, but would it work?
The new one I want will need 600W or more, as I plan to upgrade my video cards in 1-2 years, and who knows how much power they will use by then.

After browsing newegg for a bit, Corsairs 750W PSU seems to be rock-solid, but looks overkill?

Also I can't tell the difference between these two OCZ PSUs that compensate for the price difference.

http://www.newegg.com/Product/Product.aspx?Item=N82E16817341002
http://www.newegg.com/Product/Product.aspx?Item=N82E16817341019

I could save $20 by getting Corsairs 650W instead of 750W, but I'm not sure that will cover a potentially-crossfire video card upgrade.

 

[dtemple]

Depending on the quality of your 450W, it should run your current setup just fine. I have a similar setup (higher end video card, but lower end CPU) running on a 380W Antec - Athlon X2 7750 Black Edition with an HD4830... and my voltages are spot-on. I don't think you'd necessarily want crossfire, I think you'd get better price to performance out of an HD4850, which would still run smoothly on a quality 450W with your Phenom II 940.

 

[theAnimal]

I currently have a 450W PSU, I'm not expecting it to run even one 4770, but would it work?

HD4770 only uses ~50W, should be no problem if it's a good quality PSU.

 

[AKM880]

+1. Unless its a generic brand,

 

[ac3144]

HD4770 only uses ~50W, should be no problem if it's a good quality PSU.

I thought the 4770 uses up to 80W, which is why you still need a six pin PCIe cable going to it i.e just over the 75W that the PCIe slot can give?? Happy to be corrected if I am wrong.
AC

 

[Mousemonkey]

I thought the 4770 uses up to 80W, which is why you still need a six pin PCIe cable going to it i.e just over the 75W that the PCIe slot can give?? Happy to be corrected if I am wrong.
AC

Back in March this little known site estimated the power usage at around 80w, whether you trust that or not is up to you.

 

[ac3144]

Back in March this little known site estimated the power usage at around 80w, whether you trust that or not is up to you.

Never heard of that site..is it foreign?
AC

 

[Mousemonkey]

Never heard of that site..is it foreign?
AC

Dunno, it's all greek to me.

 

[theAnimal]

I thought the 4770 uses up to 80W, which is why you still need a six pin PCIe cable going to it i.e just over the 75W that the PCIe slot can give?? Happy to be corrected if I am wrong.
AC

xbitlabs measured it at 49.5W during 3dMark06.

 

[Mousemonkey]

Sounds like we need the owner of one to come forth and let us know whether it can run without the PCIe power feed.

 

[ac3144]

Sounds like we need the owner of one to come forth and let us know whether it can run without the PCIe power feed.

Would it damage your motherboard in anyway do you reckon to run it without a cable, or would it just not work? (I may experiment to find the TRUTH!!)
AC

 

[Mousemonkey]

Would it damage your motherboard in anyway do you reckon to run it without a cable, or would it just not work? (I may experiment to find the TRUTH!!)
AC

I have only tried it with Nvidia cards, but it should either just beep like mad or as the case with an nvidia card an error box pops up stating that the card is not receiving enough power as well as the beeping, can't remember which OS or driver version I was running when I got the error message but the beeping should be universal. I don't think any damage should be incurred either by the motherboard or the card though as both my 8800GT's are still running and they have had times when the plugs have not been in properly.

 

[loneninja]

I think it was Guru3d that came to the conclusion the 4770 uses 73W under load. Either way that card is a beast for its power consumption, blows my 4670 away for Performance/Watt.

 

[Mousemonkey]

I think it was Guru3d that came to the conclusion the 4770 uses 73W under load. Either way that card is a beast for its power consumption, blows my 4670 away for Performance/Watt.

I think he be be right. linkage

 

[ac3144]

I think it was Guru3d that came to the conclusion the 4770 uses 73W under load. Either way that card is a beast for its power consumption, blows my 4670 away for Performance/Watt.

So ~50w is incorrectamundo yes?
AC

 

[theAnimal]

So ~50w is incorrectamundo yes?
AC

No, that is actual measured power consumption by the video card. Guru3D only measured system power consumption, so there is no way to tell exactly how much of that was the video card. I highly doubt you could stress only the video card without putting some added stress on the CPU, RAM and mobo.

 

[Mousemonkey]

No, that is actual measured power consumption by the video card. Guru3D only measured system power consumption, so there is no way to tell exactly how much of that was the video card. I highly doubt you could stress only the video card without putting some added stress on the CPU, RAM and mobo.

Well they do have a nice little chart here, but it's this bit where they mention ATI that caught my eye.

Our normal system power consumption is higher than your average system. The results:

* System in Idle: 232 W
* GPU stressed 100% : 305 W

Roughly 305 Watt, which is really fine. 305-232 = 73W which rhymes well with the 80W TDP ATI claims.

 

[ac3144]

No, that is actual measured power consumption by the video card. Guru3D only measured system power consumption, so there is no way to tell exactly how much of that was the video card. I highly doubt you could stress only the video card without putting some added stress on the CPU, RAM and mobo.

Hi Animal, I'm not being awkard towards you, so please don't think that. The reason I ask is that if power consumption is lower it would free up some power for a few more system fans in my case
I might try it at the weekend...if you see a big smoke cloud to the East...that'll be my computer ..
AC

 

[theAnimal]

Well they do have a nice little chart here, but it's this bit where they mention ATI that caught my eye.

Our normal system power consumption is higher than your average system. The results:

* System in Idle: 232 W
* GPU stressed 100% : 305 W

Roughly 305 Watt, which is really fine. 305-232 = 73W which rhymes well with the 80W TDP ATI claims.

TDP does not equal power consumption.

 

[Mousemonkey]

No it's heat but 50w power will give less than that.

 

[k0unit]

The PSU is questionable, but not complete garbage. It looks like it'll actually give me about 422W on 12v rails after reading the specs.
It doesn't have the 6pin PCIe power connector, which also gets me a little worrisome.
What I could do is buy one HD4770, and if it doesn't work up to par I can get a new PSU.

A little dangerous if it overheats etc, but sounds good?

 

[theAnimal]

No it's heat but 50w power will give less than that.

It's not actual heat, but maximum heat that the cooling system is required to dissipate. If you look at the TDP for i7 for example they are all 130W even though the chips run at different speeds and therefore have different power consumption and heat output.