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[ale] tips on buying ATI / AMD graphics cards



Hi all,

It just so happens I've been buying some ATI / AMD graphics cards lately 
for use in doing computations for cryptocurrency mining, ie Bitcoin / 
Litecoin.  Since it's been a while since I've been in the market for 
GPU's, I've learned a few things about buying them.  I thought I'd pass 
a few tips along.  These are just my opinions so adapt for your use and 
your mileage may vary, etc.  Big caveat - I AM NOT USING THESE FOR 
GAMING.  I'm using them for computations.  However, the card I'm going 
to recommend does very well with modern games based on reviews on 
Newegg.  Another caveat, I'm focusing on one particular ATI / AMD card 
that meets my needs.  I have no way of comparing other cards.  For that, 
I would recommend the following resources:

http://www.pcper.com/ - PC Perspectives
http://twit.tv/twich - This Week in Computer Hardware Podcast
http://www.computerpoweruser.com/ - Computer Power User Magazine - 
downloadable for free, by the way
http://www.maximumpc.com/ - Maximum PC Magazine - older ones 
downloadable for free

By the way, not related to the specific cards I bought, I experienced a 
new kind of computer hell the other night and a new definition of pain.  
I managed to crash the video driver on my Mint machine and booted into 
nothing but a black screen.  Eventually, I got to a text screen.  I got 
it fixed, barely, without reformatting the hdd and reinstalling the OS 
on my Mint machine.  It taxed my Linux skills, such as they are, and was 
very frustrating.  I'll write up the details later when I have the time, 
I hope.

I've always liked the ATI / AMD product line and those cards are very 
good for coin mining and gaming, as it turns out, so that's what I'm 
focusing on.

The first card I bought was an Asus HD-7850.
It was this one: ASUS HD7850-DC2-2GD5-V2 Radeon HD 7850 2GB

I was looking for something at Frys originally which was fairly modern 
and powerful and still had a decent price point.  This is the one that 
caught my eye.

Based on the reviews at Newegg, this is a good card, and the one I'm 
using is working for me.  However, I wouldn't recommend it.  The reason 
is that it is extremely long, around 11".  It barely even fits in my 
chassis without hitting the hard drive cage.  It makes wiring around it 
very hard.  Supposedly, it runs quieter and cooler than some of the 
competition.

Having bought that card though, which I'm still using, I decided to 
stick to other 78xx cards for any others that I would buy, and 
preferably 7850 ones.  By doing this, I get consistent performance and 
power consumption across all cards.  I also only have to deal with only 
a few sets of parameters for setup.  Finally, if I did want to game with 
them and put them into crossfire mode, you have to have cards in the 
same series to connect together.  So, anything else I use with crossfire 
would have to be at least a 78xx card.

I bought another card off the Frys shelf, again based on what impressed 
me on the packaging and the price.
It was this one: MSI R7850 Twin Frozr 2GD5/OC Radeon HD 7850 2GB

I really like this card, and it's the one I'd recommend if you're 
looking for an HD 7850 card.  It also has good reviews.  I also really 
like the MSI brand, and have two of their motherboards.  Note the OC in 
the name.  This card is designed with overclocking in mind.  I'm not 
doing that myself, but it's good to know it has a beefier design with 
perhaps more thermal headroom.

This card currently lists for $ 220 on Newegg and sometimes has rebates.

Here are several things I'd suggest looking for when buying graphics 
cards (in no particular order).

* Check the slots on your motherboard.  These cards fit in a PCI-E slot 
but they are double width.  They will cover up the next adjacent slot on 
your motherboard.  Using 2 cards in crossfire mode will cover up 4 
slots.  For my purpose, I may put up to 4 cards on one motherboard.  You 
would probably never need more than 2 cards for gaming.  If you did want 
to crossfire 3 cards or 4, each middle card would have to have TWO 
crossfire connectors on each card.  You gang card 1 - 2 and 2 - 3 and 3 
- 4.  Based on what I've heard, you get diminishing returns after the 
second card in crossfire.  The card I'm recommending has only one 
crossfire connector, so you could only gang 2 of them together.  You 
could, however, use this card on either end of a 3 or 4 card setup.

For the motherboard, I managed to get the last MSI 890FX motherboard 
with 5 PCI-E slots that Frys had.  This board can hold 4 double width 
GPU's.  Most newer motherboards can only hold 3 double width GPU's.  On 
my motherboard, the 5th PCI-E slot is between some of the others, so I 
cannot use it.  Again, with gaming, versus mining, you'd probably only 
need two anyway.

* Check your case / chassis if you're planning on filling up the 
motherboard with GPU's.  My motherboard has 7 total slots.  But, an 
older case I had was a 7 slot case.  Sounds fine.  However, the last 
card is jammed up against the power supply.  That means I cannot put a 
double width card in the last slot on the motherboard.  For that, even 
with a 7 slot motherboard, you need an 8 slot or 9 slot case.

* Look for 2 fans on the card.  This means more airflow, less noise, 
better cooling, and you have some redundancy if a fan fails.  The MSI 
card has 2 fans.

* Just my personal preference, look for at least a 3 year warranty.  The 
MSI card as a 3 year parts, 2 years labor warranty according to Newegg.

* Look for a card with a SINGLE rather than a DOUBLE 6 pin PCI-E power 
connector.  Most power supplies can accommodate an 8 pin connector, but 
I haven't seen any of those.   You have to provide this extra power 
circuit from your power supply, which will use up one of your cables for 
each card.  If the card has two connectors, I would THINK that it would 
be less efficient under full load.  In that case, I don't know if you 
can run it lightly loaded with one cable connected or not.  The MSI card 
has a single power connector.

* Look at the card's length.  As I mentioned, the long Asus card made it 
very hard to install and wire around it.  Just eyeballing my full tower 
case, I wouldn't want to put any card longer than 9.25" in it.  The MSI 
card I'm recommending is only 7.76" long.  This leaves a fair amount of 
space between it and the HDD cage in the chassis.

* The card should have support for ATI / AMD's Eyefinity multi display 
technology.  I think most, if not all, modern ones do, even if the box 
doesn't say so.  Note that going beyond 2 displays requires a display 
with a display port connector or an active display port adapter to 
convert from another port type.  I encountered this trying to connect a 
second DVI monitor to my GPU.  The active display port to DVI adapter 
adds another $ 100 or so to your cost.  The MSI card supports Eyefinity.

* Look at the output ports that the card has.  The MSI card I mentioned 
has DVI, HDMI, and two mini display port connectors.  Note that you 
would need an adapter or special cable to plug in a full size display 
port connector.  Note that you can connect VGA to DVI using an adapter.  
These are often supplied with the cards.  Note also that DVI comes in 
single link and dual link varieties.  Dual link is better, and allows 
for higher bandwidth and resolution.  I don't know the specs off the top 
of my head, but you might want to look it up.  The card's package 
doesn't always say which connector is there.  I think most modern cards 
are dual link DVI.

* Look at the drivers.  AMD has proprietary drivers for both Windows and 
Linux, which I'm fine with.  If you want open source, you'll have to do 
homework to see if that exists.  I don't know.

* Look at the amount of video RAM on the card.  I recommend at least 2 
GB.  This helps for the computational application I'm doing, but it also 
helps for games, since it allows more texture maps, etc. to be loaded 
into RAM.  The MSI card has 2 GB or RAM.

* The card should support the Crossfire multi GPU technology so you can 
gang them together.  I think almost all, if not all, modern cards do, 
even if the box doesn't mention it.  But, you might want to verify it.  
Crossfire cards will have a small ~ 1" edge connector on the top of the 
circuit board near the rear of your computer chassis.  You use a 
crossfire connector, a special ribbon cable, to connect two or more 
cards.  As stated above, if you want to gang more than two cards 
together, your number 2 card if ganging 3 or your numbers 2 and 3 cards 
if you're ganging 4, will need TWO crossfire connectors.  You can use 
cards with single crossfire connectors on either end of your gang of 
cards.  Crossfire connections are not necessary or relevant, as far as I 
know, for using the cards for cryptocurrency mining.  If the cards were 
ganged together, I don't know what effect, if any, it would have on mining.

* Finally, look at what accessories that come with the package.  Newegg 
provides a picture of this.  The MSI card I recommended comes with two 
power adapters, a DVI - VGA adapter, a mini display port - display port 
adapter, and a crossfire bridge cable.

Well, those are my observations from my recent experience.  I hope you 
find them helpful.  Feel free to add to them.

Sincerely,

Ron


-- 

(PS - If you email me and don't get a quick response, you might want to
call on the phone.  I get about 300 emails per day from alternate energy
mailing lists and such.  I don't always see new email messages very quickly.)

Ron Frazier
770-205-9422 (O)   Leave a message.
linuxdude AT techstarship.com
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