Slow HDD test results: Symptom of slow PC or the cause?

My computer is very slow at the moment and the only thing that I can think that has changed is the disk space utilisation. I did a test of my HDD read/write performance which seems slow for my drive.

Are the low results a consequence of the overall slow PC or the cause?

CrystalDiskMark Results:

      Read[MB/s]   Write[MB/s]
Seq   93.30        83.65
512K  29.85        39.49
4K    0.353        1.074

CrystalDiskMark Resuls (SAFE MODE)

      Read[MB/s]   Write[MB/s]
Seq   99.56        85.35
512K  32.38        39.88
4K    0.365        1.027

AFTER FIRMWARE UPDATE...

CrystalDiskMark Results:

      Read[MB/s]   Write[MB/s]
Seq   101.7        90.24
512K  36.93        42.8
4K    0.444        1.008

PC Details:

• Fujitsu Siemens ESPRIMO P7935 Core2 Quad 2.8GHz Q9550
• Windows 7 64-bit Ultimate
• 8GB RAM
• ST3250318AS Barracuda 7200.12 SATA 3Gb/s 250GB

Your HDD results look absolutely normal to me. I have similar results on my HDDs. For example here is my Seagate 500Gb 5400 rpm 2,5" results:

-----------------------------------------------------------------------
CrystalDiskMark 3.0.2 x64 (C) 2007-2013 hiyohiyo
-----------------------------------------------------------------------
* MB/s = 1,000,000 byte/s [SATA/300 = 300,000,000 byte/s]

           Sequential Read :    98.053 MB/s
          Sequential Write :    97.870 MB/s
         Random Read 512KB :    39.699 MB/s
        Random Write 512KB :    46.976 MB/s
    Random Read 4KB (QD=1) :     0.519 MB/s [   126.8 IOPS]
   Random Write 4KB (QD=1) :     0.867 MB/s [   211.6 IOPS]
   Random Read 4KB (QD=32) :     1.201 MB/s [   293.2 IOPS]
  Random Write 4KB (QD=32) :     0.863 MB/s [   210.6 IOPS]

  Test : 500 MB [E: 82.0% (382.1/465.8 GB)] (x2)
  Date : 2014/04/18 17:49:36
    OS : Windows 7 Ultimate Edition SP1 [6.1 Build 7601] (x64)

And here is the result of 250 Gb Seagate ST3250410AS 7200 rpm SATA2

To be more precise, I would say your results are absolutely normal for your HDD and they are not slow (though of course you can get higher performance with modern 7200 rpm HDDs and much higher performance with an SSD).

Check Seagate for a firmware update. These drives had serious problems when they first came out. Read some of the Amazon reviews.

http://www.amazon.com/Seagate-Barracuda-Cache-Internal-ST3250318AS-Bare/product-reviews/B002NBIPOW/ref=cm_cr_pr_link_1/181-3133808-7967926?ie=UTF8&showViewpoints=0