i5 + AMD 7990 build

I had intended to post this a while back I usually write some notes as I build so that “next time†I didn't forget stuff, so some of this even dates back to earlier builds. I would only build once or twice a year so i am an amateur, apologies for the long post.

Requirements.
I had wanted to upgrade my gaming PC which does 1% gaming and 99% E@H. It was running a first generation i3, and 2 nvidia GTX460s, built it in 2010, even now it's still nice to use. I knew this would mean something bigger, and been thinking it needed to support an Occulus Rift.

I like reliable and long lasting equipment. Once built, it needs to be several years before I reopen the case – I get disappointed if I don't get 5 years stable running.

Must boot-up and crunch 7x24 automatically on power up.

The nvidia was making about 95K RAC, I wanted to make something over 300K, cost about 700 and definitely must be under 1000 GBP.

Linux, because it's leaner (although dual boot is an option) and I just feel more connected with the Debian flavours.

Buying... I'm not adverse to buying second hand for some things, my rule of thumb is if there is a very good saving to be had, have it. Don't buy old stuff.

GPU cards and cases - yes, maybe CPUs, but memory, mobos PSUs no.

I'd been admiring the HD79xx RAC numbers, so I waited for the HD7990 (dual GPU card) to appear on ebay, and then decided to make a cruncher to feed it. XFX HD 7990 second hand on ebay for about a third of the new cost.

Second hand cases, always check you get all screws, fans, filters and and filler plates.

I now know ventilation and good airflow are VERY important. Next time...i might consider water-cooling – i have an idea maybe you could use it to heat domestic water.

Case Antec – Once you find a case type you like you tend to stick with it – i wanted to match my other one for no reason other than looks and had what i thought ample fan slots. Antec-ThreeHundred full size ATX case second hand on ebay included 5 fans, a PSU (450W too small), DVD an SATA removable caddy. I saved 90% on list price and budget target was assured.

New stuff

• ATX mobo Gigabyte Z97X-UD3H-BK Intel LGA1150 Z97 CPU Intel Core i5 i5-4690K
  Heat sink Raijintek EreBoss
  2x8gb DDR3 memory and
  SSD - Samsung 2.5-Inch 120 GB 850 EVO
  PSU Corsair HXi750 – expensive but i chose this for several reasons, low power wastage (**1); ability to run a USB connection to monitor voltages; modular cables seems to be the way for keeping the case tidier. (I had not used a modular cable PSU before)
  

Warning a PSU efficiency rant has been thoughtfully edited and moved to end of this post **1

Mistakes made

• 1. Check size of everything, a) before you buy and b) definitely before you start building. Just because its an ATX case and ATX motherboard it does not mean everything fits. The 7990 is a big card, 305mm long - about 5mm too long for the case! The CPU heat sink also fits, but again that was more luck than judgement. One of the modular cables is 5 cm too short, (its reaches but it's not tidy). The memory cards themselves have protruding heat sinks and that caused a problem with CPU heat sink.

2a. Metalwork 101 if you fail lesson 1. Now the 7990 fits but one HD drive slot was sacrificed.

2b. Metalwork is extremely stressful with the motherboard in. I has assembled pretty much everything (yes heat sink attached) when I discovered the length problem, and the disk chassis was integral to the case – oh dear and other four star words.

3. Check power plugs for good moulding. I kept wondering why I could not get a good connection, the plugs were very hard to engage, and just would not lock in. After cleaning excess flashing they clicked into place. I wrote a complaint to Corsair, they were poor, clearly no QC was done. I received no reply. The PSU is great, but such a pity a couple of cheap connectors spoiled it.

4. If space is tight, it may be easier to put power / data cables in place before seating motherboard, into case, or before mounting the heat sink. At least check they snap in.

5. Magnetic screwdrivers rock, I think they might be my favourite tool, since the big bang. Also good for picking up metalwork filings from lesson 2b!

6. SSD – this was my first outside a laptop - mounting is different from HDD and for some reason I thought a caddy or similar might be supplied with the case – no. Antec provide a floor mounting point for the SSD but the case did not have the special silicone grommets. Antec wanted 12 GBP to ship four grommets! I made my own from some duct tape and a hole punch in ten minutes.

7. Heat sinks... I like high efficiency air coolers because they don´t work a fan as hard, so quieter, last longer, cooler and save money. They also look good. I am glad I read some reviews online about installing this one. Some ship without a long screwdriver, and without such a thing – it is impossible to assemble. Mine arrived without one, my heart sank but an email to Raijintek in Germany had one couriered to me next day! Corsair – take note – that is service. The size of the heat sink and its fan and the protruding RAM meant the only orientation which worked was the heat sink fan pulling hot air, rather than pushing cold (see lesson 1). Not happy about that, but the heat sink is so good CPU temp rarely reaches 50C

8. Check delivery times on cheap things. No IDE on motherboards so recycling old DVD and HDD required adapters. I ordered a SATA IDE converter on order from China, delivery about 20 days!

9. Getting a GPU running boinc and E@H efficiently is a struggle the first time. Heat, and understanding what is the “runing safe†temperature range is. Heat was something I had not really noticed with 2 x nVidia gtx460s and was unprepared. Unfortunately with the front cover on, with the finest dust filter makes for hotter running, so it has been removed but this will mean over time, more cleaning.

10. Noise: Fans move air and moving air is noisy, some fans more so than others, and fan noise is cumulative, and some fan settings seem to cause a case resonance.

11. In hindsight wish I had bought an i7, but cost is high - the i5 keeps the 2 GPUs running at 98% each crunching 3 (even 4) tasks each – but with only four cores (no hyper-threading) there's no capacity I find to drive even one cpu task. There is room for some over-clocking so that avenue may be explored.

Some photos

Did anyone spot the red tape and which photo it first appears in?

OS + Boinc Install.
Being new to AMD I had wished I had read and researched some threads, I thought the hardware build was the hard part and i'd be crunching in an hour or two. I just assumed latest Ubuntu, ati drivers and boinc from the Ubuntu repository would run well.

Novice mistake, the hard part was yet to come! I logged that here Ubuntu 14 and HD79990

**1 OK here it is.... [rant-PSU-OCD]
Power supplies should be rated on their intrinsic power consumption at say 50% load, rather than some vague %efficiency value. Simply put, like every other piece of electronic equipment we buy, how much heat do they make when they are working ?

For example at 50% the HX750i uses 7% (750W maximum) which is about 26W. My older PSU ¨Bronze level¨ Corsair TX650 considered very efficient 5 years ago, is about 17% so generates 52W at 50% (for producing ~50W less power!).

The http://www.plugloadsolutions.com/80PlusPowerSupplies.aspx is excellent reference point for looking at various manufactures PSUs.

My run of thumb is 1 GBP per Watt per year so by throwing away the old PSU, and replacing it with new, after 4 years, it pays for itself.
[/rant]