<PAGE>
                                                                   EXHIBIT 10.16


                                  DOVEBID, INC.
                                  -------------

                            AMENDMENT TO CONVERTIBLE
                          SUBORDINATED PROMISSORY NOTE

         This Amendment is entered into as of June 25, 2001, by and between
William J. Gardner, Jr. ("Payee") and DoveBid, Inc., a Delaware corporation (the
"Company"). This Amendment amends the terms and conditions of that certain
Convertible Subordinated Promissory Note issued by the Company to Payee on
February 29, 2000 in the principal amount of $880,000 (the "Note").

         Whereas, Payee and the Company desire to amend the Note on the terms
and conditions set forth below;

         Now, therefore, in consideration of the foregoing and for other good
and valuable consideration (receipt and sufficiency of which is mutually
acknowledged), the parties agree as follows:

         1.   Extension of Term.  The first and second sentences of the Note are
 hereby amended to read as follows.

         "DoveBid, Inc., a Delaware corporation (the "Company"), with offices at
         1241 East Hillsdale Blvd., Foster City, CA 94404, for value received,
         promises to pay to the order of James Gardner ("Payee") at such address
         as Payee may designate in writing, Eight Hundred and Eighty Thousand
         Dollars ($880,000.00), plus simple interest thereon calculated from the
         date hereof until paid at the annual rate that shall equal: (i) 7.0%,
         compounded annually from February 29, 2000 until March 31, 2001, and
         (ii) 8.0%, compounded annually, from and after April 1, 2001. Principal
         in the amount of $220,000 and accrued interest on that portion of the
         principal will be due and payable in lawful money of the United States
         in full on February 28, 2002, principal in the amount of $220,000 and
         accrued interest on that portion of the principal will be due and
         payable in lawful money of the United States in full on August 31,
         2002, and principal in the amount of $440,000 and accrued interest on
         that portion of the principal will be due and payable in lawful money
         of the United States in full on February 28, 2004, in each case unless
         such principal and/or accrued interest shall have been previously
         converted pursuant to Section 2 below, in which case the portion of the
         outstanding principal under this Note that was converted and all
         accrued but unpaid interest thereon shall be satisfied in full by
         virtue of such conversion and the issuance and delivery of fully paid
         and non-assessable shares of Conversion Stock to the holder of this
         Note as set forth in Section 2 below. Notwithstanding the foregoing,
         the Optional Convertible Debt (as defined below) shall be immediately
         due and payable in lawful money of the United States in full upon (a)
         the sale, conveyance, lease, transfer or other disposition of all or
         substantially all of the assets of the Company to an acquirer which is
         not a reporting company under Section 13 or 15 of the Securities
         Exchange Act of 1934, as amended ("a Private Company"), or (b) the sale
         by the stockholders of the Company of the beneficial ownership (as
         defined in Section 13 of the Securities Exchange Act of 1934) of a
         majority of the outstanding voting securities of the Company to one or
         more related Private Companies, in a single


<PAGE>

         transaction or in a series of related transactions (other than open
         market purchases) which occurs prior to the Maturity Date."

          2.   Definitions.
               -----------

               2.1 Definition of Optional Conversion Debt. A new definition is
hereby added to the Note as Section 1.7 to read as follows: " `Optional
Convertible Debt' shall mean $220,000 of the principal amount of this Note, and
all of the accrued but unpaid interest on such portion of this Note."

               2.2 Definition of Mandatory Convertible Debt. A new definition is
hereby added to the Note as Section 1.8 to read as follows: " `Mandatory
Convertible Debt" shall mean all of the principal amount of this Note and all of
the accrued but unpaid interest on this Note, as reduced by any conversion
pursuant to Section 2.2 of this Note."

               2.3 Definition of Conversion Stock. Section 1.2 of the Note is
hereby amended to read as follows: " `Conversion Stock' shall mean shares of
Common Stock of the Company, with respect to conversion of the Optional
Convertible Debt, and shall mean Common Stock of the Company of the same class
of common stock that is registered by the Company pursuant to an Initial Public
Offering, with respect to conversion of the Mandatory Convertible Debt. With
respect to Optional Convertible Debt, if the outstanding Common Stock of the
Company shall hereafter be changed through a reorganization or recapitalization
into shares of a different series or class of the Company's capital stock, the
Conversion Stock shall thereafter mean the shares into which the Common Stock
was changed."

               2.4 Definition of Conversion Price. Section 1.3 of the Note is
hereby amended to read as follows: "The `Conversion Price' for Optional
Convertible Debt shall mean $8.01 per share of Conversion Stock (the "Per Share
Price"), as appropriately adjusted to reflect the effect of stock splits and
combinations, stock dividends, recapitalizations and reorganizations of or on
the Conversion Stock after the Amendment Date; provided, however, that the
"Conversion Price" for Optional Convertible Debt shall mean $6.675 per share of
Conversion Stock, as appropriately adjusted to reflect the effect of stock
splits and combinations, stock dividends, recapitalizations and reorganizations
of or on the Conversion Stock after the Amendment Date, if following the
Amendment Date the Company closes its next round of private preferred stock
financing at a purchase price that is less than the Per Share Price (as
appropriately adjusted to reflect the effect of stock splits and combinations,
stock dividends, recapitalizations and reorganizations of or on the Conversion
Stock after the Amendment Date. As used in this Note, the "Amendment Date" shall
mean June 25, 2001. For Mandatory Convertible Debt, the `Conversion Price' shall
mean the price per share that is the exact middle of the price range stated in
the Company's final amended registration statement on Form S-1, Form SB-1, Form
SB-2 or a similar successor form pertaining to an Initial Public Offering that
closes on or before February 28, 2004 (the "Maturity Date"). No conversion shall
occur and there is therefore no Conversion Price with respect to an Initial
Public Offering that closes after the Maturity Date."

          3.   Conversion.  Section 2 of the Note is hereby amended to read as
follows:

                                       2

<PAGE>

                 "2.1 Mandatory Conversion. This Note and all of the outstanding
         Mandatory Convertible Debt shall be converted into Conversion Stock at
         the Conversion Price immediately prior to the first closing of an
         Initial Public Offering before the Maturity Date. For informational
         purposes, the Company shall provide the Noteholder with written notice
         (at the most recent address for the Noteholder provided to the Company
         by the Noteholder in writing) (i) within seven days after it files with
         the Securities and Exchange Commission any registration statement on
         Form S-1, Form SB-1 or Form SB-2 (or any similar or successor form) for
         an Initial Public Offering, and (ii) reasonably promptly following the
         closing of an Initial Public Offering. Conversion as described in this
         Section 2.1 shall occur only upon the closing of an Initial Public
         Offering, provided that (i) upon the closing of an Initial Public
         Offering, the conversion shall be deemed to have occurred immediately
         prior to the first closing of such Initial Public Offering, and (ii) as
         a condition precedent or condition subsequent to conversion (the
         election between which type of condition shall be the Company's sole
         election in the Company's sole discretion), the Noteholder must
         surrender this Note for conversion at the principal office of the
         Company. Incident to any conversion, the Conversion Stock will have
         those rights and privileges, and be subject to those restrictions, of
         the shares of Common Stock as set forth in the Company's Certificate of
         Incorporation, and the Noteholder will receive the rights and be
         subject to the obligations applicable to the purchasers of Common
         Stock, provided that the sale restriction specified in Section 2.6
         below shall apply to the Conversion Stock. This Note shall not be
         convertible pursuant to this Section 2.1 and shall not be converted
         into Conversion Stock under this Section 2.1 if there is not an Initial
         Public Offering on or before the Maturity Date.

                 2.2  Optional Conversion.
                      -------------------

                      2.2.1 If not previously converted pursuant to Section 2.1
         above, all of the outstanding Optional Convertible Debt may be
         converted, at any time prior to the Maturity Date, into Conversion
         Stock at the Conversion Price in the sole discretion of the Company. To
         elect to convert the Optional Convertible Debt, the Company shall send
         written notice of its election to the Noteholder prior to the Maturity
         Date. Noteholder will thereafter deliver the original Note to the
         Company at the Company's principal office for reissunce to reflect the
         conversion of the Optional Convertible Debt. Incident to any
         conversion, the Conversion Stock will have those rights and privileges,
         and be subject to those restrictions, of the shares of Conversion Stock
         as set forth in the Company's Certificate of Incorporation, and the
         Noteholder will receive the rights and be subject to the obligations
         applicable to the purchasers of Conversion Stock, provided that the
         sale restriction specified in Section 2.6 below shall apply to the
         Conversion Stock. If the unpaid principal and accrued but unpaid
         interest on this Note exceed the amount of the Optional Convertible
         Debt at the time of conversion pursuant to this Section 2.2, then the
         amount of the Optional Convertible Debt shall be applied to reduce the
         principal and interest thereafter due under this Note in the

                                       3

<PAGE>

         order such amounts would otherwise become due and payable hereunder;
         provided, however, that if such Optional Conversion occurs before
         August 31, 2002, it shall not affect the either of the first two
         payments described in the first paragraph above. Accordingly, the
         first two payments described in the paragraph above shall remain the
         same as currently contemplated but, in the event that Optional
         Conversion occurs after either of such payments, more of the payments
         shall be deemed to constitute repayment of principal to account for
         the reduction in interest that the Optional Conversion will have
         created. If the Company fails to deliver the written notice provided
         for in this Section 2.2 prior to the Maturity Date, the conversion
         right of the Company that is set forth in this Section 2.2 shall
         terminate on the Maturity Date.

                  2.2.2 In the event of any conversion pursuant to this Section
         2.2 prior to February 28, 2002, the Company shall pay to Noteholder, in
         cash, an amount equal to the lesser of (a) an amount sufficient to
         cover the United States state and federal capital gains tax imposed on
         Noteholder as a result of the receipt of such Conversion Stock and this
         Tax Payment (as defined below) based on a 35% presumed tax rate or (b)
         an amount equal to the outstanding principal and accrued but unpaid
         interest then represented by this Note (the "Tax Payment"). The amount
         paid by the Company shall be offset first against any accrued but
         unpaid interest due hereunder and then against the outstanding
         principal amount of this Note. The Tax Payment shall be made by the
         Company not earlier than 10 days prior to the time Noteholder's capital
         gains tax must be paid in connection with conversion of this Note as
         provided in this Section 2.2.

              2.3 No Fractional Shares. No fractional shares will be issued on
         conversion of this Note. If on any conversion of this Note a fraction
         of a share results, the Company will pay the cash value of that
         fractional share, calculated on the basis of the applicable Conversion
         Price.

              2.4 Reservation of Stock. Prior to any conversion of this Note
         pursuant to this Section 2 above, the Company will take such corporate
         action and obtain such government consents and approvals as may, in the
         reasonable opinion of its counsel, be necessary to authorize the
         issuance of a sufficient number of shares of Conversion Stock into
         which this Note is to convert.

              2.5 Fully Paid Shares; Certificates. All shares of Conversion
         Stock issued upon the conversion of this Note shall be validly issued,
         fully paid and non-assessable. The certificates representing the shares
         of Conversion Stock issued upon conversion hereof shall be delivered to
         the holder against surrender of this Note upon Mandatory Conversion of
         this Note pursuant to Section 2.1 hereof or upon Optional Conversion
         pursuant to Section 2.2 hereof. The holder, by accepting this Note,
         undertakes and agrees to accept such shares of Conversion Stock in full
         satisfaction of the Optional Convertible Debt or of the Mandatory
         Convertible Debt, as the case may be, that is outstanding as of the
         effective date of conversion in accordance with the terms of this Note.
         Anything to the contrary in this Note notwithstanding, the Company's
         obligation to issue shares of

                                       4

<PAGE>

         Conversion Stock to any holder of this Note and the Noteholder's
         obligation to convert this Note or any portion hereof to Conversion
         Stock, are both expressly conditioned upon compliance of such issuance
         with applicable federal and state securities laws without registration
         or other qualification thereunder. If any Conversion Stock cannot be
         issued for any reason, then the Company will continue to be obligated
         to pay this Note at the times set forth herein.

             2.6 Restriction on Sale. Upon and following any conversion pursuant
         to this Section 2 if such conversion is in connection with an Initial
         Public Offering, no holder of any Conversion Stock shall effect any
         sale or distribution of any of the Conversion Stock (which shall
         include any and all voting securities received by such holder as or in
         connection with a stock dividend, stock split or other recapitalization
         or similar distribution on or in respect of the Conversion Stock) or
         any of the Company's other equity securities, or of any securities
         convertible into or exchangeable for such securities, during the period
         beginning on the closing of the Initial Public Offering and ending 180
         days after such closing. The certificate(s) representing the shares of
         Conversion Stock issued upon the conversion of this Note shall be
         legended to reflect such restriction on sale.

             2.7 No Rights or Liabilities as Shareholder. This Note does not by
         itself entitle the Noteholder to any voting rights or other rights as a
         shareholder of the Company. In the absence of conversion of this Note,
         no provisions of this Note, and no enumeration herein of the rights or
         privileges of the holder shall cause such holder to be a shareholder of
         the Company for any purpose by virtue hereof.

             2.8 No Other Conversion. The conversion provisions set forth in
         this Section 2 constitute the sole methods by which this Note will
         convert."

         4.  Effect of Amendment. This Amendment will be effective as of the
date first set forth above, upon execution of this Amendment by the Company and
Payee. This Amendment may be executed in any number of counterparts, each of
which shall be deemed an original and all of which, taken together, will
constitute one and the same Amendment. Except as expressly provided above, the
terms and conditions of the Note remain in full force and effect, unmodified, as
of the date hereof.

         In Witness Whereof, Payee and the Company have executed this Amendment
to Convertible Subordinated Promissory Note, in the case of the Company by a
person duly authorized to do so.

THE COMPANY:  DOVEBID, INC.                PAYEE:  WILLIAM J. GARDNER, JR.


By:        /s/ Anthony Capobianco              /s/ William J. Gardner, Jr.
    --------------------------------       -----------------------------------
                                           (Signature of Payee)
Title:     VP and General Counsel
       -----------------------------

                                       5