Intel Core 2 Extreme QX6850 & MSI P35 Diamond mobo
Intel's fastest desktop quad-core
Review Intel is getting ready to move to a new generation of processors on a 45nm fabrication process, but that hasn't stopped it from squeezing some more performance out of its existing, 65nm chips. So, ladies and gentlemen, please welcome the 3GHz Core 2 Extreme QX6850 with the chip giant's brand new 1333MHz frontside bus.
MSI's P35 Diamond: ready for 1333
We tested the up-clocked processor on an MSI P35 Diamond motherboard - one of the first mobos to support the 1333MHz FSB - with Kingston DDR 3 memory and the results are... promising. Not earth shattering. Certainly not 'a new dawn in desktop computing', but promising.
We were disappointed by the first Intel P35-based motherboards that we saw. Intel's P965 had turned out to be a very good chipset that suffered from two related PCI Express problems, while the P35 added two new features without addressing either of these issues.
The new features add DDR 3 support to the memory controller alongside the existing support for DDR 2, while the CPU FSB support is extended to 1333MHz, though 1066MHz and 800MHz are also supported.
As for the PCI Express problem, the P965 only has 20 PCIe lanes, so even though many motherboards have dual graphics slots, you only get 16 lanes to one slot and four lanes to the other. The elderly 975X chipset does rather better, as it feeds eight lanes to each slot when you run dual graphics cards.
So in this regard the P965 is a step in the wrong direction and the P35 doesn't put us back on track. And it doesn't support Nvidia's SLI, so if you fancy fitting multiple graphics cards, you're looking at AMD's CrossFire or nothing. Or you could wait for the launch of the X38 chipset, which is rumoured to support both CrossFire and SLI with a full 16 lanes of PCIe each.
We started our P35 testing on an MSI Platinum with a Core 2 Extreme QX6800 processor running at 2.93GHz with 2GB of Kinston KHX6400 DDR 2 memory. We used a mediocre Nvidia GeForce 8600 GTS graphics card as we weren't putting an emphasis on gaming ability. If we'd run an AMD ATI Radeon HD 2900 XT it would have simply lifted the performance for each test system, instead of highlighting the differences.
MSI's P35 Platinum: impressive
The results are impressive and would undoubtedly make the basis of a decent PC, but it was time to try some new shiny stuff. We switched the MSI Platinum for an MSI Diamond, which supports DDR 3 memory as well as DDR 2, but looks very similar to the Platinum in every other respect. The layout is fairly standard MSI fare, although the top half of the board is dominated by the Circu-pipe cooling system.
MSI has linked up the four passive coolers on the southbridge, northbridge and power regulation hardware with heatpipes. The passive coolers are larger than normal and the heatpipes are looped round to pack extra length into the limited space. Added to that the heatpipes are finned to increase their surface area.
It's a serious piece of engineering that keeps the motherboard hardware cool. However, the P965 required minimal cooling so we consider this to be something of a negative for the P35.
The MSI has routed three heatpipes around the eight-pin ATX 12V connector so it's just about possible to connect and disconnect the power supply but it's a bit of a fiddle. To make life easier, the board includes an extender for the power connector, but it's a mark of things that this should be necessary.
MSI's Diamond: power connector extender
The rest of the layout is neat and tidy. However, you'd be well advised to use the lower of the two long PCIe slots for your graphics card as the top slot is uncomfortably close to the southbridge cooler, which is so tall that it will clash with a hefty graphics card. You'll also find that the memory retention latches are obscured and two of the SATA connectors are unusable. Furthermore, the memory slot that is closest to the processor socket sits very close indeed to the Circu-pipe system so you may well find that one component heats up the other.
It' clear that MSI has worked hard to sort out the motherboard cooling but it has had knock-ons in the areas that we have mentioned. MSI has added an interesting feature in the shape of a PCIe-connected Creative X-Fi audio riser card but what we're really interested in is the DDR 3 memory support.
MSI's Diamond P35: X-Fi add-on bundled
We plugged in 2GB of Kingston KHX11000 memory, which runs at an effective speed of 1066MHz compared to the 800MHz of the KHX6400. The SiSoft Sandra benchmarks showed memory bandwidth and latency improved to the tune of 10-15 per cent, which doesn’t seem especially impressive as the clock speed increased by 33 percent however DDR3 has much greater latencies than DDR2 and we were impressed that even these early examples of DDR3 offer increased performance over fast DDR2.
SiSoft Sandra memory tests
Memory latency in ns
Shorter bars are better
Memory banwidth in MBps
Longer bars are better
The effect of DDR 3 showed up as an improvement of nine per cent in the memory element of PCMark05 and as three per cent in the overall result, but you certainly pay for the privilege as 2GB of DDR 3 costs £300 - the same amount of DDR 2 can be had for less than £100.
Longer bars are better
Our third set of tests were run with the new Core 2 Extreme QX6850, which uses a 1333MHz FSB to achieve a clock speed of 3GHz so it's only fractionally faster than the 2.93GHz QX6800, while the TDP remains the same at 130W. The increase in FSB means that the clock multiplier drops from 11x to 9x, but the benefits to performance are rather limited.
SiSoft Sandra showed a 12 per cent increase in memory performance while the memory test in PCMark05 came up with a six per cent benefit and a four per cent overall improvement. That's worth having, but most of the increase is thanks to the small increase in clock speed, rather than the FSB.
Time in seconds
Shorter bars are better
In and of itself the move to 1333MHz is largely irrelevant. However, this will be the last hurrah for the 65nm 'Kentsfield' core before Intel makes the move to 45nm 'Penryn', when we can expect clockspeed increases to 3.33GHz, 3.67GHz and beyond.
Like all members of the Core 2 Extreme family, the QX6850 sells for a huge amount of money so we'll be comparing the more reasonably priced 1333MHz FSB-friendly Core 2 Duo E6750 with the old-style E6700 on the same MSI Diamond platform in the very near future.
The transition to DDR 3 memory and the 1333MHz FSB offers an incremental increase in performance that's a step in the right direction. In that respect, they are very welcome. The problem is that DDR 3 costs a fortune compared to DDR 2. But the 1333MHz FSB is effectively free of charge so if you have a straight choice of 1066MHz or 1333MHz we'd strongly suggest that you go with the new speed.