The enthusiast audience waited throughout 2012 for AMD to come up with a dual GPU HD7970 solution. In the end they failed to deliver, so it fell onto partners to create a solution. Powercolor, VTX3D and Club3d all released the HD7990 last year – a monster dual GPU designed to battle head to head with the Nvidia GTX690.
We reviewed the VTX3D HD7990 on December 29th and it walked away with one of our highest awards, due to a competitive price to performance ratio.
Parting with £680 for a graphics card would seem a completely insane move for most people, but it is worth remembering that the Nvidia GTX690 still retails around the £800-£850 mark. Trying to work out ‘value for money’ at this price point does seem crazy.
We won’t retread old ground today, if you want to catch up, then follow the link above for the review on the single HD7990. When I initially reviewed the card I smiled when I saw the Crossfire connector bundled in the box. Quadfire was something I wanted to try, but at the time I couldn’t get my hands on two of the cards.
I received a couple of emails since the review launched. ‘Hey man, any chance of testing with two HD7990s?’ came the call from a hard core bencher based in California.
A very friendly chap near London was determined to pick up two of the cards from DABS, but wanted some reassurances it would work well. There certainly is not much point spending £1,400 if you are only left with an expensive bookend.
Sadly, If history has taught us anything then AMD certainly haven’t had a reassuring track record with QUAD Crossfire. Without preempting the results below, I was sadly proven right. Even after multiple operating systems were installed from fresh with a handful of recent AMD drivers.
I managed to get my hands on a 10cm Crossfire connector, the longest you can get. We had to route the connector inside the cooler on the first card (as shown in the image above), otherwise it wouldn’t stretch across the three slots to the next VTX3D HD7990.
We tested with the following system.
Processor: Core i7 3960 X Extreme Edition @ 4.4ghz
Cooler: Antec 920 H20
Memory: 16GB G.Skill 2,400mhz @ 10-11-10-30
Motherboard: Asus Rampage IV Extreme (latest 3301 bios updated for the review)
Power Supply: Enermax Platimax 1200W and Seasonic Platinum 1000W
Optical Drive: Asus BluRay Drive
Chassis: Lian Li PC-A77FR Aluminium Red Full Tower Case
Boot Drive: Patriot WildFire 120GB
Secondary Drive: 1TB Samsung
Monitors: Dell U3011 and Dell U2410 x 3.
To power a system like this, you need a hell of a power supply.
We tested with both the Enermax Platimax 1200W and the Seasonic Platinum 1000W. This was to verify that the many crashes we experienced were not related to a power related issue. The system was taking around 800W at the socket under load, so both supplies were perfectly within specifications.
On the I/O plate of the VTX3D HD7990 is a red button. This is a dual button BIOS switch, with both core speeds configured to a turbo of 925mhz. You can however only overclock this card with the button pressed inwards. If you want to overclock at all, ULPS needs to be disabled. Open REGEDIT, search for ‘enableULPS’ and change the registry value from 1 to 0.
Due to instability we never got around to overclocking the cards, however in the case of the review today, we wanted to ensure ULPS wasn’t causing a problem. So we disabled it.
We tested with the latest beta drivers. In fact we had so many problems we tried multiple versions of AMD’s drivers released since November last year. It didn’t make a difference to resolving the array of hardlocks and system crashes.
The cure? Simply to remove one of the cards.
We did manage to get some benchmarks to complete however, but games such as Max Payne 3 wouldn’t even detect the second card was installed. Sleeping Dogs saw a 15% increase in frame rate at 2560×1600. Dirt Showdown and F1 2012 would both crash on startup, as would the latest Batman game.
3DMark 11 would crash regularly at random times. Once it completed a run with a score of 15,300 points, which compares to 15,113 points from the single card. On screen stutter was horrific too. Something was definitely not right.
Trying to test across 3 screens was an unmitigated disaster too.
Unigine Heaven Benchmark 2.0 completed every time, and we scored an average of 219 frames per second, compared to 168 frames per second with the single HD7990. £680, or £13.30 pence per frame (for the 51 extra frames per second) seems tough to justify.
We really do have to fault the AMD drivers for these negative results, which were very disappointing. AMD can say that the HD7990 isn’t an ‘official’ part, so optimisations won’t be forthcoming, but we have experienced this before with 4 GPU Crossfire in the past.
We can’t imagine many people would want to spend £1,400 on two of these graphics cards, although I know for a fact there are at least a handful of people who would have wanted such a kick ass, crazy system in their house.
Our conclusion? We advise against it and need to lay the blame with AMD’s drivers.