7870 and 400W PSU

[wolf0x]

I bought a 7870 just yesterday and it just hit me that I didn't check if my PSU was good enough for it. I know AMD recommends a 500W one but I figure they may overestimate, so can anyone tell me if I'll be good with this set up i.e. not toast my whole rig or should I really get a new PSU.

Intel i3 530
Corsair 4GB RAM
HD 7870 (5770 currently which 'needs' 450W)
400W Corsair CMPSU-400CXUK/400CX
Gigabyte H55M-UD2H

 

[ASHISH65]

no get new one.500w is must

 

[ARICH5]

give us a link to the corsair....I only recommend HIGH quality psu's for a question like this. like 80+ silver and above. if that corsair is a 80+ bronze id say no...don't do it.

 

[wolf0x]

This is the one: http://www.corsair.com/builder-series-cx400.html

I kinda thought I might have to replace but after just shelling out for the graphics card I'd rather not 😀

Any recommendations on a cheap but reliable replacement would be great

 

[wolf0x]

Feel free to add anymore opinions, I'm now on the fence seeing as I have varying replies.

 

[fkr]

that is a good seasonic unit i beleive. also tested out to 450W
275 watts for the 7950
75 watts for the i3
at full load i doubt you would break 400 watts and since this can run up to 475 watts you can do it.

http://www.hardwaresecrets.com/article/Corsair-CX400W-Power-Supply-Review/750/8
they have it running just under 80% efficiency and making 475 watts
you have a 30 amp 12v rail so you can push 350 watts to that graphics card.
i would read that review and maybe
http://enthusiast.hardocp.com/article/2009/02/16/entry_level_power_supply_roundup
I think you have enough there to make this work. if it is the seasonic I think it is I would risk it. but that is just my opinion.

 

[ARICH5]

id say don't risk it.....you always wanna be 100% sure that it will work when dealing with psu's otherwise you take the whole rig out. headroom and safety is the way to go.

 

[wolf0x]

id say don't risk it.....you always wanna be 100% sure that it will work when dealing with psu's otherwise you take the whole rig out. headroom and safety is the way to go.

Really?! Does it actually fry your rig if it's not sufficient

 

[ASHISH65]

Well it fries in rare cases.specially gpu is the first target of that!

 

[fkr]

he will not be pushing over 375 watts and his power supply should do 100 more watts. thats is 20+% headroom. if you went to my links at the usage he should be at he will still have 83% effeciency and even if he maxes it at 400 watts it will run at 80% effeciency. how much head room is good and what numbers are you using to figure out if he has enough power there or not.

 

[ARICH5]

http://www.tomshardware.com/answers/id-1639677/psu-discussion-veterans-great-watts-amps-debate.html#10594575

fkr..we only give recomedations of underwattage psu's to 80+ silver or over. many veterans support this claim so without dragging out boring calculations and e-peens I recommend you do the same. and if you wanna debate this more message me in that thread.

@OP...risk is not a word used in psu questions. I have seen psu's literally explode due to underwattage situations. if this is a economical reason I suggest you save money. and if you cannot afford a psu upgrade and you wanna risk this? go ahead, but no veteran builder will touch this thread.

 

[ARICH5]

http://www.tomshardware.com/answers/id-1639677/psu-discussion-veterans-great-watts-amps-debate.html#10594575

in that thread we have an electrical engineer with c++ and a++ cerification and a few veterans debating this subject.

 

[wolf0x]

http://www.tomshardware.com/answers/id-1639677/psu-discussion-veterans-great-watts-amps-debate.html#10594575

fkr..we only give recomedations of underwattage psu's to 80+ silver or over. many veterans support this claim so without dragging out boring calculations and e-peens I recommend you do the same. and if you wanna debate this more message me in that thread.

@OP...risk is not a word used in psu questions. I have seen psu's literally explode due to underwattage situations. if this is a economical reason I suggest you save money. and if you cannot afford a psu upgrade and you wanna risk this? go ahead, but no veteran builder will touch this thread.

Okay thanks, I really don't want to risk it so I'll go for a new one, any makes I should avoid or go to?
Found one, is it a good one to go for both reliability and price? Corsair CP-9020047-UK (~£45)

Its a 500W btw

 

[fkr]

I 100% agree that if you have the money for a new power supply then go ahead and get one. I also believe that 50-100 watts is the bare minimum for overhead wattage to have for a system at load. this puts him at running 80% of capacity at full load (350/400-450 watts). Considering that this seasonic unit runs at 80% efficiency till 450 watts I think that is an acceptable number. It is kinda surprising that they have not labled it that way.

 

[ko888]

Is your graphics card a Radeon HD 7870 GHz Edition (i.e. Pitcairn XT) or Radeon HD 7870 Boost Edition (i.e. Tahiti LE) version?

The minimum power requirements are different because they each use a different GPU model.

Graphics card manufacturers determine the minimum power supply requirements by taking the graphics card's power consumption under a typical gaming load and add that to the power required to run a system, excluding the graphics card, based on a PC configured with an Intel Core i7 Socket 2011 3.2GHz processor. The system includes the motherboard, CPU & stock Intel included cooler, memory, optical disk drive, hard disk drive and chassis including cooling fans. A 50 Watt allowance is added to handle some of the weaker (i.e. lower quality) power supplies.

Total Power Supply Wattage is NOT the crucial factor in power supply selection!!! Sufficient Total Combined Continuous Power/Current Available on the +12V Rail(s) rated at 45°C - 50°C ambient temperature, is the most critical factor.

The +12 Volt continuous current rating is determined by taking the graphics card's +12 Volt current draw and adding it to the 15 Amps allotted for the remainder of the Intel Core i7 Socket 2011 3.2GHz based system.

I prefer to use the graphics card's power consumption when running FurMark, instead of the power consumption while gaming, to give power supply recommendations because I'm not naive enough to think that users don't run FurMark.

At least with my recommendation the PSU won't shut itself down because it has exceeded what it can handle because it wasn't taken into account.

When asking for a PSU recommendation please supply the exact brand and model number of the graphics card so a more precise recommendation can be provided. I will always try to look up the measured power consumption for a specific graphics card model if it's available.

For a system using a single AMD reference design Radeon HD 7870 GHz Edition graphics card AMD specifies a minimum of a 500 Watt or greater system power supply. The power supply should also have a maximum combined +12 Volt continuous current rating of 28 Amps or greater and have at least two 6-pin PCI Express supplementary power connectors.

For a system using a single AMD reference design Radeon HD 7870 Boost Edition (Tahiti LE) graphics card AMD specifies a minimum of a 500 Watt or greater system power supply. The power supply should also have a maximum combined +12 Volt continuous current rating of 32 Amps or greater and have at least two 6-pin PCI Express supplementary power connectors.

Overclocking of the CPU and/or GPU(s) will require an additional increase to the maximum combined +12 Volt continuous current ratings, recommended above, to meet the increase in power required for the overclock. The additional amount required will depend on the magnitude of the overclock being attempted.

 

[wolf0x]

Is your graphics card a Radeon HD 7870 GHz Edition (i.e. Pitcairn XT) or Radeon HD 7870 Boost Edition (i.e. Tahiti LE) version?

The minimum power requirements are different because they each use a different GPU model.

Graphics card manufacturers determine the minimum power supply requirements by taking the graphics card's power consumption under a typical gaming load and add that to the power required to run a system, excluding the graphics card, based on a PC configured with an Intel Core i7 Socket 2011 3.2GHz processor. The system includes the motherboard, CPU & stock Intel included cooler, memory, optical disk drive, hard disk drive and chassis including cooling fans. A 50 Watt allowance is added to handle some of the weaker (i.e. lower quality) power supplies.

Total Power Supply Wattage is NOT the crucial factor in power supply selection!!! Sufficient Total Combined Continuous Power/Current Available on the +12V Rail(s) rated at 45°C - 50°C ambient temperature, is the most critical factor.

The +12 Volt continuous current rating is determined by taking the graphics card's +12 Volt current draw and adding it to the 15 Amps allotted for the remainder of the Intel Core i7 Socket 2011 3.2GHz based system.

I prefer to use the graphics card's power consumption when running FurMark, instead of the power consumption while gaming, to give power supply recommendations because I'm not naive enough to think that users don't run FurMark.

At least with my recommendation the PSU won't shut itself down because it has exceeded what it can handle because it wasn't taken into account.

When asking for a PSU recommendation please supply the exact brand and model number of the graphics card so a more precise recommendation can be provided. I will always try to look up the measured power consumption for a specific graphics card model if it's available.

For a system using a single AMD reference design Radeon HD 7870 GHz Edition graphics card AMD specifies a minimum of a 500 Watt or greater system power supply. The power supply should also have a maximum combined +12 Volt continuous current rating of 28 Amps or greater and have at least two 6-pin PCI Express supplementary power connectors.

For a system using a single AMD reference design Radeon HD 7870 Boost Edition (Tahiti LE) graphics card AMD specifies a minimum of a 500 Watt or greater system power supply. The power supply should also have a maximum combined +12 Volt continuous current rating of 32 Amps or greater and have at least two 6-pin PCI Express supplementary power connectors.

Overclocking of the CPU and/or GPU(s) will require an additional increase to the maximum combined +12 Volt continuous current ratings, recommended above, to meet the increase in power required for the overclock. The additional amount required will depend on the magnitude of the overclock being attempted.

Well its is GHz version and the PSU has 39A combined so I felt that was enough and I know Corsair is a good brand so I went for it

 

[ko888]

Well its is GHz version and the PSU has 39A combined so I felt that was enough and I know Corsair is a good brand so I went for it

The Corsair CX500 is more than sufficient so you made the correct choice.

 

[wolf0x]

Awesome thanks a lot all you guys, you've really saved me here. Toms Hardware proves again it is really the best place for tech help 😀

 

[ASHISH65]

Yes it is BEST palce!

 

[Sojourner]

Is your graphics card a Radeon HD 7870 GHz Edition (i.e. Pitcairn XT) or Radeon HD 7870 Boost Edition (i.e. Tahiti LE) version?

The minimum power requirements are different because they each use a different GPU model.

Graphics card manufacturers determine the minimum power supply requirements by taking the graphics card's power consumption under a typical gaming load and add that to the power required to run a system, excluding the graphics card, based on a PC configured with an Intel Core i7 Socket 2011 3.2GHz processor. The system includes the motherboard, CPU & stock Intel included cooler, memory, optical disk drive, hard disk drive and chassis including cooling fans. A 50 Watt allowance is added to handle some of the weaker (i.e. lower quality) power supplies.

Total Power Supply Wattage is NOT the crucial factor in power supply selection!!! Sufficient Total Combined Continuous Power/Current Available on the +12V Rail(s) rated at 45°C - 50°C ambient temperature, is the most critical factor.

The +12 Volt continuous current rating is determined by taking the graphics card's +12 Volt current draw and adding it to the 15 Amps allotted for the remainder of the Intel Core i7 Socket 2011 3.2GHz based system.

I prefer to use the graphics card's power consumption when running FurMark, instead of the power consumption while gaming, to give power supply recommendations because I'm not naive enough to think that users don't run FurMark.

At least with my recommendation the PSU won't shut itself down because it has exceeded what it can handle because it wasn't taken into account.

When asking for a PSU recommendation please supply the exact brand and model number of the graphics card so a more precise recommendation can be provided. I will always try to look up the measured power consumption for a specific graphics card model if it's available.

For a system using a single AMD reference design Radeon HD 7870 GHz Edition graphics card AMD specifies a minimum of a 500 Watt or greater system power supply. The power supply should also have a maximum combined +12 Volt continuous current rating of 28 Amps or greater and have at least two 6-pin PCI Express supplementary power connectors.

For a system using a single AMD reference design Radeon HD 7870 Boost Edition (Tahiti LE) graphics card AMD specifies a minimum of a 500 Watt or greater system power supply. The power supply should also have a maximum combined +12 Volt continuous current rating of 32 Amps or greater and have at least two 6-pin PCI Express supplementary power connectors.

Overclocking of the CPU and/or GPU(s) will require an additional increase to the maximum combined +12 Volt continuous current ratings, recommended above, to meet the increase in power required for the overclock. The additional amount required will depend on the magnitude of the overclock being attempted.

I'm actually asking for a 7870 card recommendation to fit the existing PSU. It has the following characteristics (currently running a Radeon HD 5770 which has crapped out)

Max 700W
+3.3V.......Min 1.0A Max 24A
+5V..........Min 1.0A Max 32A.....200W combined
+12V1.....Min 0.5A Max 21A
+12V2.....Min 0.5A Max 22A......480W (38A) combined
-12V........Min 0A Max 0.6A........7.2W
+5VSB....Min 0.1A Max 2.0A.....10W
There are 2 6-pin power connectors available though only one is currently in use

700W total power exceeds the 500W, and 38A exceeds the 32A combined 12V rail voltage, so now the question is which manufacturer's card maximizes cooling and minimizes power consumption (and thus heat generated), with 2GB onboard RAM.

The only other stuff in the system are a cheap sound card, one R/W DVD, and the HD. Oh yeah, and the fans - 3 internal fans mounted in a ThermalTake V3 case - one front mounted, one side mounted, and one rear mounted. I'm not planning on adding anything else to it either. 6GB RAM - 3.2GHz CPU (i7 I think). Running 64 bit Win7 on that machine.

The GPU drives dual monitors. Mostly I watch internet TV on it and play a few games (no online MMORPGS). Civ IV and V, Elder Scrolls, Dragon Age, and the Witcher games are the newest things I ever run; mostly I play really old legacy RPGs such as Hero's Quest and Monkey Island.

The old 5770 ran at the top of its heat range pretty much all the time (and that's probably what finally killed it). From the charts that I've seen, the 7870 actually runs a little cooler, but given I have very limited options for additional cooling in that case (the only place I could mount an additional fan is MAYBE on the bottom, the top mount is blocked by the RAM on the MB and all other spaces are populated) my main concern is cool running and minimum additional power draw to help with that. I know it's going to draw more power than the 5770 did - the difference in active temperature between the AMD cards reviewed on this site I assume is due to better cooling in the newer card, despite the additional power consumption.