Content first posted on 18/06/01

Why Dual Processors:

It may be argued that home computers are already powerful enough for Word and Outlook. However, it is increasingly common that home PCs are used for demanding games, CPU intensive tasks like 3D rendering and other applications that could still use more power. Small offices often handle large databases, design websites, and use power hungry applications like CAD and Photoshop. All these tasks benefit from the extra punch the Poweroid 7004 packs. But where you’ll find the most difference is in graphics. Image editing. 3D rendering, high end games & CAD should show simply massive improvements over any existing PC model, on any processor/platform.

The concept of using dual processors has been confined to servers, largely because of the costs involved. If you based your purchase on the dual Intel Xeon, prices started from around the £6,000 mark.

The Price: Is the price worth the extra power this technology offers? Users wanting more power than a top-end Athlon/P4 PC for their graphics work have no option but to spend several thousand pounds on a hardware solution. This machine should prove a welcome relief to their wallets.

The Technology: AMD is a new entrant to the dual processor market. While they have made considerable in-roads into Intel’s dominance of the desktop market there is considerable debate as to whether they will convince the IT manager that the AMD processor makes for a stable and cost effective alternative to Intel based servers.

Irrespective of how that debate turns out, our use of the dual Athlon processors makes for a powerful, stable and affordable workstation with more power than many of the servers in the market today.

AMD’s release of the 760MP chipset is particularly significant for the amount of testing that went into its development. This virtually guarantees it to be the most reliable chipset ever for the Athlon processor. On the CPU front, although the server version of the Athlon processor, the Athlon MP, is the only version validated by AMD for operation in multiple processor mode, it is not the only version that works in MP configuration. In fact most of the testing of the 760MP chipset was done on CPUs based around the Thunderbird cores.

Does AMD allow the use of "standard" CPUs on the 760 MP? AMD does not say whether the standard "Thunderbirds" will work on the 760MP. As the 760MP is targeted at the server market they would probably prefer it is used with the more expensive MP processors. However, we have found no clause imposed by AMD restricting the use of the Thunderbirds on the Dual processor chipset, providing the CPUs and chipset are not over-clocked. So we decided to test the platform, and impressed the IT press with the power and quality of the Poweroid 7004. While we have won "Best Performer" awards in the past for various other PCs, PC Plus went so far as to give us an exceptional "Fastest Ever PC" award for the Poweroid 7004 with good reason. It simply is.

Server vs power PC, the balancing act:

Graphics As this machine is targeted at the performance graphics, 3D and CAD end of the market, the onboard graphics that would normally have been suitable for a server is highly inadequate. We therefore disabled it in favour of a GeForce 3. On it's own the GeForce 3, 64 MB DDR is a card for the power user. However, we have configured it to an even higher level of performance through the use of special drivers and our own in-house expertise.

What about video editing: If what you are looking for is a Digital Video editing platform we can discuss offering this technology with various digital video editing cards including the Miro Pinnacle DV200 and "realtime" video editing cards like the DV500 PLUS. Please call for details. These are at extra cost. For serious video editing work we do offer larger hard disks, and options on removable storage if you anticipate large archives.

Windows 2000. While Windows 2000 is not the operating system of choice for most home and small office users Microsoft is nevertheless pushing the market towards a single operating system. It is expected that Windows XP will serve both the home and the corporate markets, and is to replace both Windows ME and Windows 2000. Windows 2000 is also currently the O/S of choice for the more technically astute users using Power PCs, as it offers considerable performance (and stability) advantages over Windows ME. Also, Windows 2000 supports MP configurations. We will not be offering the option of Windows XP on the dual processor PCs till we have done our own extensive in-house tests. This could take a month or two after release of Windows XP.

Striping – RAID 0: Many performance PCs in the market today are using IDE RAID 0 to boost their hard disk performance and therefore their overall SYSmark/Worldbench scores. We choose to use a software IDE RAID controller like the FastTrack 100 over a hardware RAID controller like the SuperTrak 100 because it actually provides better performance. Though hardware RAID uses slightly less CPU time as it does the parity bit calculation on the card itself, the hardware RAID uses its own co-processor that’s considerably slower than the CPU. We found that the slightly higher CPU utilization by the software RAID was a small price to pay for the CPU (rather than the co-processor) handling the striping. It appears that the software RAID uses very little CPU time and, as the CPU is a lot more efficient at handling breaking of files into stripes and deciding which drives to send the data to, the overall disk performance was better with the software RAID.

Cooling and cabling: PCs with single Thunderbird processors have always run very hot because of the quite substantial heat generated by the CPU. When you decide to use two Thunderbirds, and a 450 watt PSU, heat management is a major issue. Fortunately there are ample power connectors on the motherboard. In addition to the two capable heat sinks and fans on the processors, and the extra cfm capacity of the PSU fan, we’ve opted for two additional case fans to keep the temperature down. Our tests on the Poweroid 7004 showed the processors running at an acceptable 54 degrees after prolonged benchmarking use.

Can this PC be faster?

How about replacing the IDE with SCSI? We’ve tested Ultra 160 SCSI hard disks, both in RAID 0 and as standalone hard disks but even the 10,000 rpm disks, striped, do not offer more than a 2.3% increase in overall performance. The 15K SCSI disks offered an even more disappointing performance with a 2.7% increase in disk intensive applications and disk benchmarks like Disk Winmark. We decided to stick with the IDE RAID, but we do offer SCSI as an option. Please call for details.

ECC DDR SDRAM: As with any server we had to use registered RAM which does impact slightly on performance. While it is more stable, it is a bit slower - even when it is PC2100. Is 512 MB sufficient for this beast? We did test this machine with 256, 512  and 1024 MB of ECC DDR SDRAM. While a server would probably benefit more from the extra RAM, going beyond 512 MB on this model does not seem to be improving graphics scores at all, so we opted for using less RAM and giving customers the option of upgrading at an extra charge.

MP processors with the Palomino core vs Athlon Thunderbirds: The MP processor does offer some benefits, in particular a full implementation of Intel’s Streaming SIMD Extensions - SSE - (and of course 3D Now). In its favour it consumes less power, generates less heat, and offers other improvements.

The Second Great Benefit of the MP processors is the enhancement to the CPU’s Translation Lookaside Buffers (TLBs). The TLB, which caches translated memory addresses to aid in faster retrieval of data from main memory, now offers 40 entries in the L1 data TLB as opposed to the 32 in earlier CPUs. This should result in the CPU finding more of what it needs in the TLB, and making less trips to the main memory.  However, 40 entries in the TLB is still far below what’s offered by the PIII, and it still doesn’t make a big difference. The new “speculative reloading” feature, where the TLB loads an address in anticipation of a request for that address is, according to AMD, now used by some high-end software applications. All these improvements do make a difference, but it seems that the difference is small. In the graphs attached at the end of this document the tests with the two MP 1.2 Athlons show a marginally better performance over the two standard 1.2 Athlon Thunderbirds.

This is a surprising result. If the MP CPU isn’t much faster, then has the long wait for its development been in vain? On the contrary, it has been more than worthwhile. Applications that are designed specifically for MP operation show a big speed gain when used on 2 x MP processors. When used as a database server this machine will undoubtedly benefit from switching to the MP, largely for the MPs improved data pre-fetch mechanism. However, this machine is targeted squarely at the graphics end of the market and the improved data pre-fetch seems to benefit database serving rather more than 3D rendering.

What is interesting however is that many applications like Photoshop that haven’t been fully optimised for MP operation show a substantial improvement when used on the 2 x MP CPUs instead of single CPU (possible reasons explained below). What is even more interesting for the purpose of the Poweroid 7004 is that these 3D and graphics programs also show substantial improvements when used on the 2 x Thunderbird processors. 

In conclusion:

If using two Athlon Thunderbirds gives a performance on graphics applications almost on par with that of two MP CPUs, then using two Athlon Thunderbirds would make for Dual MP type performance, but with considerable cost savings.

More importantly, from the performance point of view, this opens up the possibility of using faster CPUs than are available with the MP i.e. the 1.33 and 1.4 GHz Thunderbirds. And that’s what we’ve done with the Poweroid 7004.