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Upgrading 7850 to 7870

Last response: in Graphics & Displays
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February 21, 2013 6:18:40 PM

I recently bought a 7850 (http://www.newegg.com/Product/Product.aspx?Item=N82E168...) for my old prebuilt pc (Gateway FX6840) and I'm thinking of returning the card and getting a 7870 instead, probably this one: http://www.newegg.com/Product/Product.aspx?Item=N82E168...

My question is, will that stress my PSU too much? My PSU is a 500W by FSP group with a dual 12V rail (18.0A on each rail) and 360W total on the 12V. I think that comes out to 30 amps, which is exactly what the 7870 needs, while the 7850 wants 24 amps. Is that cutting it too close?

Some specs:
CPU: Intel i7-860 at 2.8GHz
GPU: Radeon HD 7850 2GB
PSU: FSP 450-60EP (500W peak, 18.0A on each 12V rail for 360W total)
RAM: 8GB DDR3 1333MHz (4x2GB sticks)
Chipset: Intel H57 Express

Also on a side note, I'm hearing a sort of rattling sound coming from my card. It seems to get louder every now and then whether or not it's under load, then gets quiet. Is that normal?

More about : upgrading 7850 7870

February 21, 2013 7:24:36 PM

its fine. Its is recommended to get 500W or higher by amd, so you just made it.
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February 21, 2013 8:28:21 PM

I'm a little more worried about amps... I'm hearing different things about what a 7870 needs. I'm hearing everything from 27 to 35, so I'm really not sure.
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February 21, 2013 8:36:09 PM

Hi, I would say that you are pushing it, your power supply is 500 W PEAK, meaning its probably from the numbers rated for 450W and its a few years old. PSUs lose a bit of juice over time, so I personally wouldnt be happy living on the edge with an old no name Power supply like that. I would be worried it would blow, and the 7870 while better then a 7850 isn't a massive jump, Save your money and put it towards a new system. :)  EDIT Or just get a new PSU first of course.
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February 21, 2013 8:45:09 PM

I heard FSP made solid PSUs. Is that not true?

Do you think it's even safe to keep using my 7850? I've only been using it for a day.
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February 21, 2013 8:54:47 PM

That maybe true I cant find a review for your specific model, However the 500 W peak rating does denote that it works at 500 watt under perfect conditions and not for sustained periods. I think the 7870 is pushing it to a level I personally would be scared of.

As far as your card goes its definitely not normal for it to be rattling, I couldn't tell you what it is but if you've only had it a day its probably still under warranty?
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February 21, 2013 9:02:33 PM

I'm not really sure how to describe the noise, rattling was just the best I could do. It might just be that the fan sounds different than I'm used to, since my old 5570 was almost completely silent.

Edit: I should probably add that I practically have to put my ear right next to the case to hear it.
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February 21, 2013 9:25:26 PM

Have you tried forcing the fans on your card to full In Catalyst Control Center? if the noise is fan related that would make it obvious. If its not the fans, which it doesn't sound like if your saying its doing it randomly I'm afraid I wouldn't know.. I would keep an eye on the temps using GPUZ as well if you are not already they shouldn't be getting over 75 C max really under load probably lower, and it should be idling at 30-35 , perhaps someone else passing will have a better idea if your temps are all ok?
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February 21, 2013 9:33:42 PM

The FSP 450-60EP sticker shows the two 18A rails are combined( the 360 Watt max on the sticker). So 360 watt / 12 volts = 30Amps total Almost no multi rail PSU's actually have more than one 12v rail internally, its mostly marketing, as it is with this PSU as two 18A rails should max at 432 watts not 360 watts. With that said 30A should work fine but it is tight.
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February 21, 2013 9:47:31 PM

Running furmark for 15 minutes had me hovering around 65 C max, and it seems to idle right at 30 C. The fans sound just fine at 100%, so I suppose it's not that.

I can't even hear it anymore, honestly. I've been checking throughout the day and haven't really heard anything abnormal. I'm wondering if it's just my mind playing tricks on me.

So, it sounds like the 7870 might be a bit too much for this PSU, but the 7850 should be alright?

Edit: Newegg's PSU calculator seems to think as much, too. It says I'd need 405W for the 7850 and 464W for the 7870, so if my PSU is actually 450W and not 500, that's obviously too much.
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February 21, 2013 11:41:19 PM

Best answer selected by mtrochil.
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