December 14, 2004 by Edward Ng

INTRODUCTION

Silent PC Review is no stranger to Antec cases. Today we take a quick look at their SLK2650-BQE (Black Quiet Edition) midtower. Because there are many similarities between Antec offerings, this review will rely extensively on previous reviews of the Antec SLK3700-BQE and the Antec SLK3700-AMB. The primary point of differentiation is the integration of the Intel-specified, "Chassis Air Guide," which dramatically effects the type of system air flow design possible with this case, compared to the other models.

Features: Thermally Advantaged Chassis for use with, "Prescott," P4 Chassis Air Guide (on side panel) provides room temperature air directly to CPU cooler Ultra quiet single fan 350W SmartPower ATX12V power supply - for AMD™ and Intel® systems - SmartPower runs cooler and quieter 2 Front USB ports with shielded cables Removable Side Panels Removable Drive Cages 8 Drive Bays - External: 4 x 5.25", 2 x 3.5" - Internal: 2 x 3.5" Cooling capacity: - 1 120mm rear (standard) - 1 80mm front (optional) - Chassis Air Guide (standard) with optional 80mm fan Motherboards up to Standard ATX Fan Specs: RPM: 1200 CFM: 38.94 dB(A): 25 NOTE: As usual, fan specifications should be taken with a grain of salt. The specifications also list, "Removable Side Panels," (plural), but in reality, only the right side panel (the left side when seen from up front) can be opened. The top and left side of the case are a single, nonremovable piece.

What's Included?

WYSIWYG:
1. Useful installation guide
2. Fold-out instructions for connecting the USB headers
3. A pair of thumb screws for tool-free handling of the side panel
4: Hardware for mounting of components
5: Power cable for the PSU

ON THE SURFACE

Let's peel away at the case in layers, beginning from the outside...

From the Toyota Camry School of Design: unassuming and unoffensive for wide appeal.

The 2650-BQE's design is very similar to the 3700-BQE's. The only difference is that the 2650 has six rounded intake slots, while the 3700 has seven. Multiple LEDs are included for those with multiple drive controllers with activity indicator connections.

Drive rails on just one side? Don't worry; it makes sense once we get inside...

Behind the door, things look a little different. While the 3700s both have a plain, flat interior bezel, the 2650-BQE's plastic bay covers are held in place with a single tab and can be removed directly from the front. A single notch for each bay provides access to the locking tab for the drives. It is is still necessary to open the side panel to remove the drive, thus preventing drive theft as long as the side panel is locked. On the lower portion of the front bezel beneath the door are two USB ports. There are no IEEE1394 or audio ports.

Not-too-free-flowing intake, common with SLK3700-BQE.

The front intake leaves a lot to be desired, with no dust filter and narrow pathways. Also, little in the way of modification can be done to the plastic bezel due to its relatively shallow design

Prescott life-preserver?

Here, we can see another departure from the design of the 3700s: No side panel latches, and the introduction of an Intel-spec, "Chassis Air Guide." This side panel duct allows Antec to mark this product as an Intel-certified, "Thermally Advantaged Chassis," helping to bring cool outside air to the CPU. The vent is fairly free flowing, but unfiltered—bad for dusty environments. It is this specific component that marks the greatest departure from SLK3700-BQE/-AMB.

The thumb screws for the side panel allow tool-free access to the interior, and a padlock hasp is provided for security. The side panel is awfully tight, however, taking a great deal of force to get it to slide back for release, and the small notch towards the rear doesn't help much. Presumably it will become loose over time with many openings and closings.

Hardware box, panel lock tab and relatively open exhaust grill are fairly thoughtful, if not very useful touches.

Antec's low impedance rear grill from the 3700-BQE is implemented on this model. One difference from the two 3700s is that the fan is mounted via screws with silicone washers for dampening of fan vibrations. The stock fan includes silicone washers attached to it, but changing to a quieter fan will lose you nothing; the washers are much too stiff to to any good in the first place.

Flanged fan screws with silicone washers—too stiff to do much good, though.

Another change is that the I/O shield and expansion slots are flush with the back face of the case, with the ledge for securing expansion cards protruding out of the case. Normally, this type of design creates a slight security vulnerability by leaving the expansion card screws out in the open for easy access by screwdriver-wielding do-badders, but Antec's designers put quite a bit of thinking into this, as well. They came up with a black plastic tab-lock shroud-cum-hardware box that cannot be removed without access to the case interior, and even numbered the expansion slots in industry-standard order.

So that's where my darn screws went!

UNDER THE SKIN

Next, let's unmask the face of SLK2650-BQE and see what we find...

Vibration- free, tool-free rail retention, good. Breakaway bay shields that leave sharp points, bad.

Getting the front bezel of SLK2650-BQE off isn't that difficult, considering only one side panel comes off. Antec implemented an all-tabs, tool-free system for the bezel. That the side panel (which can be secured with padlock) must be removed first is a welcome degree of security. The spare drive rails latch onto the metal bay shields securely enough that the rails do not rattle from vibration. However, the twist-n-break metal shields each leave two sharp points in an otherwise safe case from getting cuts and scrapes. The grill on the 80mm intake is not as free flowing as it could be, particularly considering the more open exhaust grill. Another offset grilled opening above the intake seems almost an afterthought.

On the inside of the side panel is the item of focus, an intake duct to the CPU area. While the 3700s rely solely on the front intake to bring cool air into the system for all components, this design allows for much cooler air, unwarmed by other system components, to be used for cooling what is normally the hottest part of a modern PC, the CPU.

The duct is actually a two-piece system, comprised of a flanged bucket that screws in behind a stamped grille on the side panel, and a flared conical piece that is free to extend as much as ~1.25" into the system to deal with coolers of varying height; however, I would've preferred the duct to reach a tad farther in. The way the duct flares out works well for non-stock coolers implementing >60mm fans, and for dealing with varying positions of the CPU on different mainboards, but a flaw in Antec's design leaves a total of 16 side panel holes improperly lined up to the duct's flange, possibly reducing airflow and increasing turbulence.The duct is also extendable as much as ~1.25" to deal with coolers of varying height The other minor flaw is that the adjustable, flared portion is too loose on the flanged bracket, with a potential for the entire adjustable piece to fall off in transit if extended to the limit, but this is easily dealt with using some duct tape. Testing will focus on the effectiveness of this component.

DIVING IN DEEPER

Finally, let's look inside and see what else we can find...

Tool-free drive latches are secure and leave no slack at all, eliminating, "rail rattle!"
Large plastic rounded sleeve safeguards against sharp trailing edge of the 5.25" bay, another thoughtful touch.

One innovation on the SLK2650-BQE is the system for mounting half-height components. The tool-free rail system is comprised of a plastic rail that latches very securely to one side of the drive with a metal clip, and a plastic sliding rail on the other side. Once the component and rail are slid fully into position, the cage-mounted rail is slid back until it locks in place by squeezing against the component; the rounded black sleeve acts as a bump-stop for full engagement.. It secures the device from theft when the side panel is locked, and eliminates annoying, "rail rattle". The only flaw is that the system is almost completely incompatible with components that do not have screw holes in the standard locations, primarily 5.25" bay fan controllers. Antec would've done better to implement this system on two or three bays, while leaving at least one bay with standard screw holes.

The removable 3.5" drive bay is also quite different from the removable bays in 3700-BQE and 3700-AMB. The 2650-BQE has a single removable cage with two secure slots for screwing in external 3.5" components, and two rubber grommeted internal bays underneath that. If Antec had aligned the 80mm intake fully with this removable cage, this arrangement would be optimal. The design is highly suitable for suspension of drives bay taking advantage of either the rubber o-rings, or the openings for them, and the wide open space underneath the cage. It's too bad that intake is a relatively restrictive, off-kilter 80mm fan cage.

The plastic cage itself is typical: restrictive of airflow, unfiltered against dust and likely to be prone to rattling, as is with all tool-free fan cage mounts. A flaw in this particular enclosure's design has the fan cage misaligned with the drive cage by over an inch, too. Luckily, it IS removable and no modification is needed for full elastic cord suspension of hard drives drives. It is better, at least in this regard, than the 3700-BQE/-AMB.

Tight, but still clear enough to work in, case lacks removable mainboard tray;
the fact that the mainboard must come out for PSU installation/swapping exacerbates the issue.

The fact that the front fascia has one less intake slot than SLK3700-BQE is evidence of this case being less tall and tighter to work in. In order to fit the 120mm exhaust, Antec had to push the power supply up past the side panel latching lip. The end results is that to install or remove the power supply, the motherboard must not be installed. A removable power supply mounting plate (of the kind used in the Silverstone TJ06, for example), would allow for access to the PSU from the outside of the case. The shorter design also means there's not enough space for a 120mm intake fan without sacrificing a drive bay, which I felt would have been wiser.

An Antec SL350S power supply unit is included with 2650-BQE. Sold only with Antec enclosures, the SLxxxS models are SmartPower units modified by the removal of the bottom intake fan for lower noise. Efficiency of this somewhat aging design is only about average, as past tests have shown to be around 65-68% at average power draw levels (100-150watts) reaching up to around ~74% in the units', "sweet spot" at about 2/3 of maximum power. Because of the lower efficiency, this PSU gets warmer than the newer, more efficient units, which now run at or close to 80% even at modest power levels. The PSU fan speed regulator tends to ramp more than we PC silencers like to hear.

My own listening tests revealed that the 80mm fan in this sample is smoother than the than the 80mm Super Red unit in a Seasonic Super Silencer, which has a more ragged sound to it, but has to spin faster (and thus, louder) to deal with the lower efficiency. The 120mm Yate Loon fan in the Super Tornado, however, is smoother and quieter than the 80mm fans in either the SL350S or the Super Silencer. For the purposes of the acoustic and thermal testing on this enclosure, I opted for the popular Seasonic Super Tornado unit, a common unit for members to swap out the stock unit for. It is not likely that the average PC silence seeker would settle for the acoustic performance of the stock SL350S.

Grommets and screws: they might have worked—were they not stiff as stone.

THE INSTALLED SYSTEM

The enclosure was purchased with a specific application in mind: fanless utilization of a Thermalright XP-120 cooler in an Athlon 64 system, which necessitated an Intel-spec TAC (Thermally Advantaged Chassis).

SLK2650-BQE's special test bed, a balance of drive thermal management
and fanless CPU cooling, making use of the, "Channel Air Guide."

Key Components in SLK2650-BQE & Fanless XP-120 Test Bed

AMD Athlon 64 3000+ NewCastle core—AMD-specified MDP 89.5Watts
Antec SLK2650-BQE midtower ATX enclosure—stock fan swapped for Nexus silent 120, controlled via software
DFI LANParty UT nF3 250Gb mainboard—nVIDIA nForce3 250Gb chipset, on-die CPU thermal diode monitoring
Thermalright XP-120 CPU HS—fanless, relying on side vent and back exhaust fan for sufficient air flow
eVGA GeForce2 MX400 PCI graphics adapter—passively cooled
Generic DDR SDRAM—one stick, 256MB
Maxtor DiamondMax 9, 6Y060L0—7200rpm, 3.5", 60GB PATA HDD with one platter and two heads
SeaSonic Super Tornado 400—Revision A3, unmodified from stock
Arctic Silver V thermal compound

TEST RESULTS

Test Tools

CPUBurn load-induction software—To test at maximum thermals
Prime95 load induction and stability testing software—In-Place Large FFTs Torture Test was utilized
ITE Smartguardian system monitoring and fan control software supplied with motherboard
Motherboard Monitor 5.3.7.0 system monitoring software
Seasonic Power Angel AC level power monitoring tool

The heatsink was cleaned and the thermal interface material was allowed to properly set by cycling between completely off and full load several times over 24 hours. All stress tests were run a minimum of 25 minutes to allow stabilization of temperatures, with 20 minute cool down periods between test runs.

AC power consumption was measured, and temperatures of the HDD, CPU, MOSFETs and chipset were recorded. The exhaust fan was connected to the motherboard CPU fan header, which was regulated during all tests by the ITE Smartguardian software. The fan was set to spin down at 40°C and lower. Spin up was set for 55°C, and maximum spin rate was to occur at 70°C.

The system was tested in three different states of operation: Idle, Prime95 with In-Place Large FFTs, and finally, CPUBurn for maximum CPU stress.

The PSU fan speed was also monitored with the RPM lead connected to a motherboard header. It never left the range of 620-630rpm during all testing, so it has not been indicated in the charts. It is the only fan operating in the system during a much of the testing.

The CPU voltages utilized were the lowest stable voltage for the tested clockrate. Undervoltability will vary from sample to sample. The test results show the possible yields when undervolting a Newcastle-core K8 chip, as well as how underclocking and undervolting affect the overall power consumption of the system as a whole. Let's see how much heat, in conjunction with a relatively powerful cooler, Antec's little TAC can handle, and how well the case performs, from an acoustic standpoint...

• When idling, the CPU's power draw has a virtually negligible effect on the overall AC consumption. It is not until 1800MHz and 1.125V that the CPU power draw adds noticeably to idle power draw.

• The hard drive, temperatures are still within acceptable levels (Maxtor states 55°C max), even without direct airflow, or conduction to the chassis as it is mounted via the stock rubber o-rings. It appears that there is sufficient air coming in from the front of the case to cool the drive, just from the negative pressure produced by the PSU fan, which remained at ~625rpm during all tests.

• All temperatures are within perfectly safe levels.
  
  
• The acoustic performance of the system during all the IDLE tests was, with the exception of hard drive whine, best described as inaudible, or, "virtually silent." Considering no modifications were done to reduce drive acoustics, these results are excellent.

• Subjectively, the Nexus 120mm does not add noticeable noise to the system when spinning at a leisurely ~600rpm, even with the relatively low ambient noise level during late night testing; the stock mounted hard drive remained the primary noise source.

• Hard drive temperatures also drop a fairly decent ~5°C across the board once the fan spins up, and this can further improve by taping shut any openings that do not directly flow into critical components, thus allowing negative air pressure to further increase flow across components in the remaining air streams.

• AC power draw finally breaks into the triple-digit territory for this system at the 2200MHz mark; so much performance for so little heat and power!

• Thanks to the 120mm exhaust fan, spinning at a very nearly inaudible ~600rpm, temperatures easily remained with acceptable bounds.

• Temperature is up across the board except for the hard drive, confirming that CPUBurn as the best choice for CPU loading and heat production.

• The fan actually exceeds 700rpm during the overclocked testing, reducing the hard drive temperature further; the fan was only barely noticeable at 730rpm, but still more than acceptable for all but those seeking absolute, dead silence. The HDD is still the loudest part of the system, by far.

• The increased AC power draw is also indicative of how much additional, "juice," it takes to drive CPUBurn as compared to Prime95. Several SPCR forum members have mentioned that Small FFTs place a heavier load on the CPU than Large FFTs, but Large FFTs loads the RAM, which, neither Prime95 Small FFTs, nor CPUBurn manage to do. In testing for undervolting stability, it is useful to also load the memory, because the K8 memory controller is on-die, and possibly affected by undervolting or overclocking. Even at such a heavy thermal load (CPUBurn is a much heavier load than any normal usage would ever apply), the SLK2650-BQE's design allows for perfectly acceptable temperatures when utilized in conjunction with an undervolted K8.

Additional Noise Comments

• One minor acoustic flaw was that the the stock-mounted hard drive conduct enough vibration into the case to make the 5.25" drive bays covers rattle slightly. Some foam or cotton to damp the bay covers from behind, or better yet, suspending the hard drive, completely eliminates this acoustic annoyance.

• The side duct/vent did not leak much noise; this is the advantage of using components that make little noise to begin with. In fact, careful listening tests from various angles revealed that more of the HDD whine leaked out through the front of the case than from the side duct.