PSU help

[BroliviaWilde]

I am going to get a second 7970 card. My question is, would my current PSU be good enough, or will I need to upgrade that as well?

Here is my pc I built last summer:

Intel Core i7-2600K 3.4GHz Quad-Core Processor - not OC

Thermaltake Water 2.0 Performer 81.3 CFM Liquid CPU Cooler

Asus P8Z77-V PRO ATX LGA1155 Motherboard

Corsair Vengeance 16GB (4 x 4GB) DDR3-2133 Memory

Samsung Spinpoint M8 500GB 5400RPM Internal Hard Drive

Seagate Momentus XT 750GB 7200RPM Internal Hard Drive

Diamond Radeon HD 7970 3GB Video Card

Antec Eleven Hundred ATX Full Tower Case

Cooler Master Silent Pro Gold 800W 80 PLUS Gold Certified ATX12V / EPS12V Power Supply

Asus DRW-24B1ST/BLK/B/AS DVD/CD Writer

I have looked at several PSU calculators and here are a couple of results I got if I had a second 7970 added to above build list:

pcpartpicker: 733W

newegg: 934w

outervision: 634w

asus: 1100w

what is interesting about the outervision site is that when I check for one card, it is rated at about 250w, but when I add the second card it rates it at 411w ... so this suggests that the second card is never going to use full power in a crossfire mode?

So the question remains, what is a good psu to use when I get a second 7970? Or would my current psu be good enough? I thought for sure that outervision was a good site, but after seeing this I am not so sure.

[Dave :)]

800W is more than enough. Generally, the recommended wattage is inflated then reality, mainly to cover their end incase something goes wrong, they aren't liable to be 'done'.

[Ghost]

If you are really worried then you should run your PC at full load while measuring at the wall how many watts your PC is drawing from the wall.

[Glenwing]

You'll be fine. The "recommended" wattage for a PSU is usually far higher than what the system actually draws, because PSUs are most efficient around 50-60% load. With dual 7970's your system will probably be drawing 500-600W.

[Dr3nz4r]

outervision is not verry accurate.. you should better sum up all TDP's of the produtcs to get some idea of its max power consumption

Since your PSU is 80+ Gold I think this shouldn't make any problems..

My Calc :

2*8Pin = max 300Watts

2GPUS á 2x8pin = max 600Watts

CPU :

Max TDP 95W (says the intel website) lets say u oc it till it draws.. 125Watts

Total of 725Watts for now which can be drawn in an ABSOLUTE 100% Peak load

Both HDD'S

Total of about 15Watts

with those we are at about 740Watts in 100% Peak load where EVERY component is drawing as much power as it CAN

Your DVD drive about 5 watts (again if you could load it up to 100%)

we're at 745Watts now.. (PS: im taking EVERY Watt value from the manufacturer's homepages and adding additional ~3% to simulate a total peak load of the component)

you should be pretty fine with some ~900Watt PSU with good efficiency.. Your's got about 91% at 100% load which means it is able to output about 728Watts..

You could stick with your current PSU, if you think you will never push everything above its limits (and again this is roughly calculated.. I've added more to my calculations like GPU's both would never get about 600Watts.. because you could not load both at 100% while everything else is at 100% too..(well by benchmarking like crazy it would be possible) because : better more then less..

If your PSU isn't good enoguh for the setup it wont break anything cuz it would turn the whole system down.. safty first and then you could even go and buy a new one instead of throwing this money out now when you do not know if you ever need a greater PSU.

Long story short:

Stick with your current one it should fit properly if you dont do hardcorebenchmarking and Overclockings and even if it's not enought: go and buy a new one :) it wont destroy anything in your build

[BroliviaWilde]

outervision is not verry accurate.. you should better sum up all TDP's of the produtcs to get some idea of its max power consumption

Since your PSU is 80+ Gold I think this shouldn't make any problems..

My Calc :

2*8Pin = max 300Watts

2GPUS á 2x8pin = max 600Watts

CPU :

Max TDP 95W (says the intel website) lets say u oc it till it draws.. 125Watts

Total of 725Watts for now which can be drawn in an ABSOLUTE 100% Peak load

Both HDD'S

Total of about 15Watts

with those we are at about 740Watts in 100% Peak load where EVERY component is drawing as much power as it CAN

Your DVD drive about 5 watts (again if you could load it up to 100%)

we're at 745Watts now.. (PS: im taking EVERY Watt value from the manufacturer's homepages and adding additional ~3% to simulate a total peak load of the component)

you should be pretty fine with some ~900Watt PSU with good efficiency.. Your's got about 91% at 100% load which means it is able to output about 728Watts..

You could stick with your current PSU, if you think you will never push everything above its limits (and again this is roughly calculated.. I've added more to my calculations like GPU's both would never get about 600Watts.. because you could not load both at 100% while everything else is at 100% too..(well by benchmarking like crazy it would be possible) because : better more then less..

If your PSU isn't good enoguh for the setup it wont break anything cuz it would turn the whole system down.. safty first and then you could even go and buy a new one instead of throwing this money out now when you do not know if you ever need a greater PSU.

Long story short:

Stick with your current one it should fit properly if you dont do hardcorebenchmarking and Overclockings and even if it's not enought: go and buy a new one :) it wont destroy anything in your build

Thanks, that has been very helpful. I will now gladly go get my second card once the wife loosens her kung-fu grip on our cash, haha

[Dr3nz4r]

outervision is not verry accurate.. you should better sum up all TDP's of the produtcs to get some idea of its max power consumption

Since your PSU is 80+ Gold I think this shouldn't make any problems..

My Calc :

2*8Pin = max 300Watts

2GPUS á 2x8pin = max 600Watts

CPU :

Max TDP 95W (says the intel website) lets say u oc it till it draws.. 125Watts

Total of 725Watts for now which can be drawn in an ABSOLUTE 100% Peak load

Both HDD'S

Total of about 15Watts

with those we are at about 740Watts in 100% Peak load where EVERY component is drawing as much power as it CAN

Your DVD drive about 5 watts (again if you could load it up to 100%)

we're at 745Watts now.. (PS: im taking EVERY Watt value from the manufacturer's homepages and adding additional ~3% to simulate a total peak load of the component)

you should be pretty fine with some ~900Watt PSU with good efficiency.. Your's got about 91% at 100% load which means it is able to output about 728Watts..

You could stick with your current PSU, if you think you will never push everything above its limits (and again this is roughly calculated.. I've added more to my calculations like GPU's both would never get about 600Watts.. because you could not load both at 100% while everything else is at 100% too..(well by benchmarking like crazy it would be possible) because : better more then less..

If your PSU isn't good enoguh for the setup it wont break anything cuz it would turn the whole system down.. safty first and then you could even go and buy a new one instead of throwing this money out now when you do not know if you ever need a greater PSU.

Long story short:

Stick with your current one it should fit properly if you dont do hardcorebenchmarking and Overclockings and even if it's not enought: go and buy a new one :) it wont destroy anything in your build

haha :D

10charr

[Electronics Wizardy]

That 800 watt psu is more than enough and will power crossfire well. these new cpu's and gpu's use so little power.