As I mentioned in my previous post, I had a power supply fan fail in one of my Dell Optiplex 755 systems. Although I received a replacement supply from Dell (the system is under warranty for another two years) I decided to look into a larger power supply, as I’d upgraded the hard drive, CPU, and video card. The standard Dell supply is only 305 watts and I expect it is running near its rated capacity.

I’ve been using PC Power & Cooling products since the company was founded – the first product I used was a fan that bolted onto the back of an IBM PC XT to improve airflow. I haven’t used their products recently, as the few systems I’ve built from scratch have come with power supplies already installed in the cases.

I took a look at their site and found the Silencer 500 Dell power supply which stated that it was a direct replacement for the Dell power supply in my Optiplex 755. It also said it was a direct replacement in 61 other Dell systems, which should have given me a clue that the unit was more generic than it was letting on.

This power supply slightly exceeds the efficiency rating of the stock Dell power supply (82% vs. 80%) while providing up to 500 watts continuous power.

I unpacked the power supply, which came in a nice printed box (my earlier PCP&C supplies had come in generic brown cardboard boxes, which indicates how far power supplies have come in being recognized as a critical component of the system). There was a huge wad of cables coming out of the supply – far more than the Optiplex 755 needed.

I did a test fit of the supply in the chassis and discovered that there were a number of problems. First, the AC power cord connector interfered with part of the case. Next, the case had tabs which were designed to slot into the Dell power supply. The PCP&C supply was lacking those slots, so it was impossible to mount the supply perfectly squarely in the case.

The first change I made was to modify the AC power cord connector on the supply so it would fit in the case. This involved cutting off the plastic “ear” on one side of the connector. Fortunately there is a metal tab on the connector which will help retain it once the power supply is installed in the chassis:

Next, I had to come up with a plan to deal with all the unused power cables:

My first idea was to tie them up neatly in the space between the power supply and the back of the DVD drives:

However, it was a very tight fit and it severely reduced the airflow through the power supply, as the vents on the inside face of the supply were nearly completely obscured by the mass of cables.

As I had already voided the warranty by trimming the power connector, I decided to open the supply and remove all of the un-needed cables. I could have cut them off outside the supply, but then I would have to individually insulate all of the cut ends and it would be really ugly.

After a brief round of cutting, the excess cables were removed:

As part of this process, I removed the floppy drive power connector (mini 4-pin) and installed it on the end of one of the SATA power cable branches. As supplied by PCP&C, the floppy connector is at the very end of a long chain of full-size 4-pin connectors (used for legacy hard drives and CD-ROMs, of which this system had none). I trimmed one of the SATA power cable branches to 2 SATA power connectors and installed the floppy connector at the end. I also removed the last connector from the other SATA power cable branch, leaving 2 connectors, and routed it down to the hard drive bay in the system. This produced a set of cables that was far more manageable:

I don’t recommend doing this yourself – aside from voiding the warranty, you could easily damage the power supply or injure yourself. PCP&C says that they don’t believe in power supplies with modular cable systems (see FAQ #3 here). However, as long as they are going to continue to represent the supply as fitting 62 different Dell models, they need to come up with some system to deal with un-needed cables. Also, it is important to remember that there are already a pair of connectors on each cable – one on the cable end and the other on the device it is plugged into. PCP&C has no control over those connector styles as they’re dictated by industry standards. But they would have unlimited choices for modular power connectors if they decided to use them.

Also, while they could justify the cables by saying that they don’t know what cards and peripherals a customer might have, there is no excuse for the interference of the power connector with the PC case – this is clearly a case (no pun intended) of someone looking at the specs of the Dell power supply and saying “sure, ours will fit” without ever checking it for themselves. It should be possible to move the power connector closer to the center of the power supply without requiring a complete re-design of the power supply and without imparing the fitment in the other Dell cases. PCP&C offers custom power supplies, but I shudder to think what the cost would be for a one-off solution to the problems I encountered.

While I’m satisfied with the solution I came up with, I can’t recommend this supply for use in the Optiplex 755 (due to the power connector mounting issue) or in any other space-limited Dell enclosure (because of the large number of un-needed cables).

Overview

It has been a little over a year since I installed three new Dell Optiplex 755 systems (see my earlier review here and here). A memory problem in one of the systems and a moaning power supply fan in another (oddly, not from cat fur) caused me to open a support case with Dell for replacement parts.

This lead to the dreaded “since I’m in here, I wonder what I could do to improve things” thoughts. Since I purchased these systems a year ago, a number of faster components have become available, or have had major price reductions. The main items that I wanted to speed up were: hard drive, video and CPU. I’ll discuss each of these in turn.

Hard drive

As I mentioned in my previous articles, I’ve been very loyal to Seagate in the past. However, they’ve fallen on their face in a number of areas recently. First, they dropped the warranty on many of their drives from 5 years to 3 years. Second, they have had some heavily-publicized firmware problems, including a “fix” that rendered some classes of drives completely non-functional. Plus, drives from other vendors out-perform the Seagate products at certain capacities. One of these is at the 250-300GB range, where Western Digital offers the VelociRaptor™. This drive is offered in 3 configurations, which differ only in the way the drive is mounted. The BLFS version is a bare 2.5″ drive, good for servers with backplanes that require this size drive. It won’t work in a notebook as it is much taller than a normal notebook drive (15mm vs. the normal 9.5mm for a notebook drive). The GLFS version is the previous drive mounted in a 3.5″ frame (which WD calls an IcePack™). However, due to the industry standards for location of the SATA power and data connectors differing for 2.5″ and 3.5″ drives, this version cannot slot in to an enclosure that has backplane connectors for 3.5″ drives. This brings us to the HLFS version, which is similar to the GLFS except that the bare drive is mounted in a slightly different location on the IcePack and there is a passive adapter board which has the connectors in the right spot for mating with SATA backplanes. Since many online merchants list the GLFS and the HLFS at the same price, I don’t know why WD bothers with the GLFS version. There are apparently some minor cooling differences between these versions, but I don’t feel they are enough to justify keeping the GLFS around.

I purchased the HLFS version as the Optiplex has a rather unusual mounting (side-to-side vs. the more common front-to-back) orientation and the cables would line up better. Plus, it would keep my options for future re-use of the drive open.

Here is the drive ready to go into the chassis. The red strip on the right side is the adapter circuit board I mentioned above:

Here is the drive mounted in the chassis. I’ll discuss the non-standard power cable in a later post:

Video card

These systems originally shipped with ATI Radeon HT 2400 XT cards. As I mentioned in my earlier review, that card didn’t support the Dual Link DVI mode that I needed to operate the 3008WFP monitor at its maximum resolution of 2560 x 1600. I replaced it with a different version of the HD 2400 that supported Dual Link. Since then, there have been a number of additional generations of ATI video cards. Unfortunately for me, most of these are dual-slot configurations due to the large fans found on the card. In the Optiplex 755, the video card occupies the uppermost slot in the chassis and there’s no place for the second bracket to go. And that is the only PCIe x16 slot on the chassis.

Looking around, I found the Radeon 3650 which was a single-slot solution. It supported the Dual Link DVI that my monitor required. It also supported the DisplayPort interface which was also found on my monitor. As finding “Built by ATI” video cards is getting harder and harder, I selected the HIS H365F512DPNP card. I have some Cyberlink software installed on this PC which requires a HDCP link to the monitor. Unfortunately, the 3008WFP monitor doesn’t support HDCP when operating in Dual Link mode, so I have to drop the resolution down to 1920 x 1200 or I get an annoying message about my display not being supported and then playback stops.

Since I now had both a monitor and a video card that allegedly supported DisplayPort at 2560 x 1600, I gave that a try. It was a total failure – the display would go into screen saver mode immediately at that resolution. At lower resolutions it would randomly cycle in and out of screen saver mode every few seconds. So much for that idea – back to Dual Link DVI. The monitor is revision A01, which according to Dell has no issues with DisplayPort. But this technology seems to not be ready for deployment.

Here’s the card installed in the system. By the way, I didn’t turn the fan so the HIS logo was right-side-up – that’s just the way the fan stopped when I shut the system down to take the picture:

CPU

I had ordered the systems with the Core 2 Quad Q6600 CPU as the only faster quad core part offered by Dell at the time was the Q6700 which wasn’t a lot faster (2.66GHz vs. 2.40GHz) and which was a lot more expensive. Since then, Dell started offering parts in the Q9xxx family. However, the top-of-the-line Q9650 still isn’t available from Dell in these systems.

Looking at the specs on Intel’s web site, I couldn’t see any reason why a system that supported the Q9550 wouldn’t support the Q9650, so I decided to give it a try. Let’s compare the specs of the Q6600 vs. the Q9650 to see what sort of performance improvements I might get:

Q6600

• 2.40 GHz clock speed
• 1066MHz bus speed
• 8MB cache
• 65nm technology

Q9650

• 3.00 GHz clock speed
• 1333MHz bus speed
• 12MB cache
• 45nm technology

The change from a 65nm feature size to 45nm means that despite the faster clock and larger cache, the thermal specification remains the same at 95W. This means that the existing CPU heatsink and fan could be re-used, which is important as the Optiplex 755 uses a custom cooling solution and not the heatsink / fan provided with the boxed CPU.

After installing the new CPU, a quick power-on test shows that the system properly detected the new CPU:

Dell systems tend to not provide the assorted overclocking tweaks found on some motherboards, so this is likely as fast as this system is going to get unless Intel releases a faster CPU. I had spec’d PC6400 memory when I ordered the systems, and that is the fastest memory the Q35 chipset supports. With 4 matching 1GB modules, the memory runs in what Intel calls “Dual Channel Interleaved” mode, which is the fastest mode. Since the motherboard doesn’t provide tweaks, this CL5 memory is the fastest that can be installed in the system. (All of the memory I’ve found that runs at CL4 and faster still reports itself as CL5 in SPD and expects the tuner to override the SPD settings).

The system is noticibly faster. Backups to my network file server run at around 70MB/second now, compared with 50MB/second before the upgrade. Windows startup is much improved.

One thing I discovered when I re-installed Windows and all my software from scratch – I had previously thought that the Intel Ethernet chipset on this motherboard didn’t support jumbo frames (because the option didn’t appear in the configuration menu as delivered by Dell). But after installing the latest drivers from Intel, the jumbo frame option appeared and I enabled it.