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Buy now, ask questions later (oops!) - Will what I bought actually work?

NutterzUK

NutterzUK

NutterzUK

Associate
Joined
18 Feb 2010
Posts
940
Hi,

I'd really appreciate any advice, perhaps I made an impulse buy.
I'm currently using a 7950, it's great and I am using it for gaming and mining. I wanted something a little faster and so bought a 7990. To be more precise, this version:
http://www.powercolor.com/global/products_features.asp?id=429#Specification

My plan is to keep my 7950, and put in the 7990 too. Of course, I only now realise it takes up 3 bays, I originally thought it was this one, which it is not: http://www.powercolor.com/global/products_features.asp?id=471

I'm ok with that since I think the price I paid was fair (there is cheaper on a certain auction site, but I don't trust that place so much).

So, will a 850w PSU power them both, and will they work together is really my question. My motherboard is this:
http://www.gigabyte.com/products/product-page.aspx?pid=3760#ov

The PSU is this: Xfx Proseries 850w Power Supply Unit (core Edition)

And it's all in an Obsidian 700d, so space isn't the big problem in terms of the case, however it does take up a lot of space on the motherboard.

So my questions are really:
- Is it ok to mix the cards?
- Will an 850w PSU be enough to power them? (and 2 hdds, 1 ssd and 24gb (6 sticks) of memory).
- Does it matter which slots they go in? I think perhaps it's best I put one in the top and one in the bottom slot to give them as much space as possible, perhaps the 7990 on the bottom and the 7950 in the top?

Thanks,
 
the 7990 and 7950 will work together, how ever i'm really unsure about 850w xfx psu.. if it was me running those 3 cards i would want at least 1000w quality branded psu. my first thoughts are the 850w xfx psu is going to be screaming its nakas off to run them at full pelt and i assume it would not last long before it went to psu heaven
 
Hi Vonex,
Thanks for your advice!
I was worrying about that. I did put it through one of the calculators which came out around 700w, so I thought perhaps 850 would be ok. Hmm. Perhaps I utilise the old PSU which I currently have installed. Is the old paperclip trick safe long term (ish), and is there any reason this would waste any more power?
 
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whats the system going to be used for?, it more then likely will be ok.. just might not last long whats the full spec of the system and is there any overclocking involved?
 
The XFX 850 is a very good PSU (made by SeaSonic) but At peak overclocked the 7990 will pull 500w and the 7950 250w, it will be running at its limit with the CPU.
 
The full system spec is:
G1 sniper 1366
i7 920 (2.6Ghz, not overclocked).
24gb (6 sticks) ddr3 corsair vengeance memory.
1 256gb SSD
2 1tb HDDs
Corsair h20
About 6 sharkoon silent eagle fans.
Mouse, keyboard, speakers, monitor etc.

I went through the calculator again, selecting "full load", and putting in all of the above (although I couldn't put in the h20, I don't think it should take too much power. The results are below)
load.png



I admit this was my main concern, but.. I can't help but think, if a PSU should work at 850w and I am using 765-815w, then why does it need to be any higher? Surely these things should be able to work flat out, if not then surely they should have been rated lower. That calculator adds some on for "recommended", I don't know if that is just to be sure, or if it's enough to add on to be sure.

I do also have a TX650w Corsair, I don't mind using it separately but I don't know if that will somehow waste extra power. I suppose the alternative is that I send my XFX back and swap it for something a bit more powerful. The XFX was £100 though, so i'll probably have to spend a fair bit more money to get something more powerful.

I don't intend to do any overclocking, at least not until I have something more suitable for a PSU.
 
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I have xfire 290s and a 2600K overvolted to 1.48v. I run them off a premium 850W PSU. I thought it would be fine but I have experienced reboots when pounding the system hard (Sleeping Dogs bench when overvolted, mining when overvolted and tweaked for max performance).
 
Orangey said:
I have xfire 290s and a 2600K overvolted to 1.48v. I run them off a premium 850W PSU. I thought it would be fine but I have experienced reboots when pounding the system hard (Sleeping Dogs bench when overvolted, mining when overvolted and tweaked for max performance).
Click to expand...

Thanks for this.

So, until I have enough money to buy a new PSU, perhaps my best option would be to try to run it with both?

If I do the following, will this work?
- Leave my Corsair TX650w powering my fans, motherboard, cpu, memory, drives etc.
- Plug in the 7990 and the 7950 into the new PSU, and do the old paperclip trick to start it up.

Is there anything (within reason) that could go horribly wrong doing this? Will it harm the new PSU to not have a motherboard connected?
 
Thanks for that link Orangey, that helped me a lot.

I think i've decided that it's probably not the best idea to use two PSUs.

So i've done some more looking into options, I can't run the 7990 with my Corsair TX 650w I don't think (correct me if i'm wrong).

==option 1==
So, perhaps I put in the new card my PC and the new PSU on their own. I then put my old card in my girlfriends machine, she gets a free upgrade (funny, her last card was salvaged from my wastefulness too!). I ask her to mine on it, I clean the pots, order Chinese food and generally be lovely and I have a chance that she will.
I'll then have a TX650 and a 6850 graphics card to sell.

==option 2==
I set up both graphics cards on my machine, that way it takes up less power overall, but may fail. I note that the PSU has a 2 year warranty, if it goes to PSU heaven, it goes back to XFS. Since the calculator etc shows it as under 850w, I don't think they can claim i've misused it in any way. I run this until I can afford a 1200w PSU, when I can, the girlfriend gets my 850w PSU as a free upgrade, and eventually, once I can afford another 7990, she gets the 7950 too. I remove some memory, the fan controller, CD/DVD drives etc which I don't use that take up power.

==option 3==
This is the best option, but requires money and patience, send the PSU back, and spend money I can't afford right now on a 1200w PSU (In a couple of months, that's np, but right now I've skinted myself a little with the 7990).


I'm leaning towards option #2 since i'm not too worried about PSU heaven, so long as my cards live on. Option 1 means leaving 2 systems on if i'm wanting to mine, and also means persuading the girlfriend. Option 3 isn't really possible until the end of the month at the earliest. I wouldn't feel right using it for a bit and then sending it back (even though I think you can within 28 days). However, I would feel less bad about it "screaming it's nakas off" and dying, then sending it back, since it shouldn't do that. Option 2 also gives me the chance that nothing goes wrong, and it runs happy as ever.
 
chaparral said:
I would go with this option...:D
Click to expand...

Ooh.. I like this one the most.. but I doubt it's happening.

At how much risk am I of causing damage running it on the 850w PSU which is possibly not powerful enough? I assume it would just restart or turn off. Is that about right? Or should I be telling my neighbors that they should rescue my girlfriend, then the cats first?
 
I wouldn't recommend a XFX power supply from my own experience. Have 2 that have died on me in the space of 12 months. They look great but unfortunatlely aren't very reliable (once again this is my own experience)
 
breadturbo said:
Unless you OC that cpu it's going to bottleneck those cards badly.

No experience of 7990's, but my old 7970s @ 1250mhz pulled 300w each
Click to expand...

They shouldn't for mining though I wouldn't imagine? I know it will for games, i've had my trusty 920 since they were first released a long time ago. It will OC to 3.2 Ghz I would think without much trouble. I did once have it at 3.8 (as per my sig).
 
I suppose I should find out - I have looked on Google and I'm struggling to find this information, are either of the PSUs group regulated?
These:
TX650w Corsair
and
Xfx Proseries 850w Power Supply Unit (core Edition)

I really lack in knowledge of these things, and I spoke to my girlfriend, mining on her PC is a no go. I'll enjoy my own Chinese food tonight :). No free 7950 for her either. Haha, joking, but i'm not allowed though :(
 
I read that the XFS has "tight DC voltage regulation" and that the TX650W doesn't have "group regulation", which makes me think it may be ok?

Hmmmmm.
 
Orangey said:
I have xfire 290s and a 2600K overvolted to 1.48v. I run them off a premium 850W PSU. I thought it would be fine but I have experienced reboots when pounding the system hard (Sleeping Dogs bench when overvolted, mining when overvolted and tweaked for max performance).
Click to expand...

1.48v on the cpu :eek:
 
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